diff --git a/openwisp_network_topology/__init__.py b/openwisp_network_topology/__init__.py
index 60e34a65..fb6d25f3 100644
--- a/openwisp_network_topology/__init__.py
+++ b/openwisp_network_topology/__init__.py
@@ -1,18 +1,18 @@
-VERSION = (1, 2, 0, 'alpha')
+VERSION = (1, 2, 0, "alpha")
 __version__ = VERSION  # alias
 
 
 def get_version():
-    version = '%s.%s' % (VERSION[0], VERSION[1])
+    version = "%s.%s" % (VERSION[0], VERSION[1])
     if VERSION[2]:
-        version = '%s.%s' % (version, VERSION[2])
-    if VERSION[3:] == ('alpha', 0):
-        version = '%s pre-alpha' % version
+        version = "%s.%s" % (version, VERSION[2])
+    if VERSION[3:] == ("alpha", 0):
+        version = "%s pre-alpha" % version
     else:
-        if VERSION[3] != 'final':
+        if VERSION[3] != "final":
             try:
                 rev = VERSION[4]
             except IndexError:
                 rev = 0
-            version = '%s%s%s' % (version, VERSION[3][0:1], rev)
+            version = "%s%s%s" % (version, VERSION[3][0:1], rev)
     return version
diff --git a/openwisp_network_topology/admin.py b/openwisp_network_topology/admin.py
index 6b54f1e4..1dfc15af 100644
--- a/openwisp_network_topology/admin.py
+++ b/openwisp_network_topology/admin.py
@@ -20,9 +20,9 @@
 from .contextmanagers import log_failure
 from .visualizer import GraphVisualizerUrls
 
-Link = swapper.load_model('topology', 'Link')
-Node = swapper.load_model('topology', 'Node')
-Topology = swapper.load_model('topology', 'Topology')
+Link = swapper.load_model("topology", "Link")
+Node = swapper.load_model("topology", "Node")
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TimeStampedEditableAdmin(ModelAdmin):
@@ -31,7 +31,7 @@ class TimeStampedEditableAdmin(ModelAdmin):
     """
 
     def __init__(self, *args, **kwargs):
-        self.readonly_fields += ('created', 'modified')
+        self.readonly_fields += ("created", "modified")
         super().__init__(*args, **kwargs)
 
 
@@ -40,21 +40,21 @@ class BaseAdmin(TimeStampedEditableAdmin):
 
     class Media:
         css = {
-            'all': [
-                'netjsongraph/css/src/netjsongraph.css',
-                'netjsongraph/css/src/netjsongraph-theme.css',
-                'netjsongraph/css/lib/jquery-ui.min.css',
-                'netjsongraph/css/style.css',
-                'netjsongraph/css/admin.css',
+            "all": [
+                "netjsongraph/css/src/netjsongraph.css",
+                "netjsongraph/css/src/netjsongraph-theme.css",
+                "netjsongraph/css/lib/jquery-ui.min.css",
+                "netjsongraph/css/style.css",
+                "netjsongraph/css/admin.css",
             ]
         }
         js = [
-            'admin/js/jquery.init.js',
-            'netjsongraph/js/lib/jquery-ui.min.js',
-            'netjsongraph/js/src/netjsongraph.min.js',
-            'netjsongraph/js/strategy-switcher.js',
-            'netjsongraph/js/topology-history.js',
-            'netjsongraph/js/visualize.js',
+            "admin/js/jquery.init.js",
+            "netjsongraph/js/lib/jquery-ui.min.js",
+            "netjsongraph/js/src/netjsongraph.min.js",
+            "netjsongraph/js/strategy-switcher.js",
+            "netjsongraph/js/topology-history.js",
+            "netjsongraph/js/visualize.js",
         ]
 
 
@@ -64,53 +64,53 @@ class TopologyAdmin(
 ):
     model = Topology
     list_display = [
-        'label',
-        'organization',
-        'parser',
-        'strategy',
-        'published',
-        'created',
-        'modified',
+        "label",
+        "organization",
+        "parser",
+        "strategy",
+        "published",
+        "created",
+        "modified",
     ]
     readonly_fields = [
-        'uuid',
-        'protocol',
-        'version',
-        'revision',
-        'metric',
-        'receive_url',
+        "uuid",
+        "protocol",
+        "version",
+        "revision",
+        "metric",
+        "receive_url",
     ]
-    list_filter = ['parser', 'strategy', MultitenantOrgFilter]
-    search_fields = ['label', 'id']
-    actions = ['update_selected', 'unpublish_selected', 'publish_selected']
+    list_filter = ["parser", "strategy", MultitenantOrgFilter]
+    search_fields = ["label", "id"]
+    actions = ["update_selected", "unpublish_selected", "publish_selected"]
     fields = [
-        'label',
-        'organization',
-        'parser',
-        'strategy',
-        'url',
-        'uuid',
-        'key',
-        'expiration_time',
-        'receive_url',
-        'published',
-        'protocol',
-        'version',
-        'revision',
-        'metric',
-        'created',
+        "label",
+        "organization",
+        "parser",
+        "strategy",
+        "url",
+        "uuid",
+        "key",
+        "expiration_time",
+        "receive_url",
+        "published",
+        "protocol",
+        "version",
+        "revision",
+        "metric",
+        "created",
     ]
-    receive_url_name = 'receive_topology'
+    receive_url_name = "receive_topology"
     receive_url_urlconf = app_settings.TOPOLOGY_API_URLCONF
     receive_url_baseurl = app_settings.TOPOLOGY_API_BASEURL
-    change_form_template = 'admin/topology/topology/change_form.html'
+    change_form_template = "admin/topology/topology/change_form.html"
 
     def get_fields(self, request, obj=None):
         fields = list(super().get_fields(request, obj))
         if not obj:
             # Receive URL cannot be created without an object.
             # Hence, remove the "receive_url" field.
-            fields.remove('receive_url')
+            fields.remove("receive_url")
         return fields
 
     def get_actions(self, request):
@@ -118,29 +118,29 @@ def get_actions(self, request):
         move delete action to last position
         """
         actions = super().get_actions(request)
-        if 'delete_selected' in actions:
-            delete = actions['delete_selected']
-            del actions['delete_selected']
-            actions['delete_selected'] = delete
+        if "delete_selected" in actions:
+            delete = actions["delete_selected"]
+            del actions["delete_selected"]
+            actions["delete_selected"] = delete
         return actions
 
-    def change_view(self, request, object_id, form_url='', extra_context=None):
+    def change_view(self, request, object_id, form_url="", extra_context=None):
         extra_context = extra_context or {}
-        prefix = 'admin:{0}_{1}'.format(
+        prefix = "admin:{0}_{1}".format(
             self.opts.app_label, self.model.__name__.lower()
         )
-        text = _('View topology graph')
+        text = _("View topology graph")
         extra_context.update(
             {
-                'additional_buttons': [
+                "additional_buttons": [
                     {
-                        'type': 'button',
-                        'url': reverse(
-                            '{0}_visualize'.format(prefix), args=[object_id]
+                        "type": "button",
+                        "url": reverse(
+                            "{0}_visualize".format(prefix), args=[object_id]
                         ),
-                        'class': 'visualizelink',
-                        'value': text,
-                        'title': '{0} (ALT+P)'.format(text),
+                        "class": "visualizelink",
+                        "value": text,
+                        "title": "{0} (ALT+P)".format(text),
                     }
                 ]
             }
@@ -148,40 +148,40 @@ def change_view(self, request, object_id, form_url='', extra_context=None):
         return super().change_view(request, object_id, form_url, extra_context)
 
     def get_urls(self):
-        options = getattr(self.model, '_meta')
-        url_prefix = '{0}_{1}'.format(options.app_label, options.model_name)
+        options = getattr(self.model, "_meta")
+        url_prefix = "{0}_{1}".format(options.app_label, options.model_name)
         return [
             re_path(
-                r'^visualize/(?P<pk>[^/]+)/$',
+                r"^visualize/(?P<pk>[^/]+)/$",
                 self.admin_site.admin_view(self.visualize_view),
-                name='{0}_visualize'.format(url_prefix),
+                name="{0}_visualize".format(url_prefix),
             )
         ] + super().get_urls()
 
     def _message(self, request, rows, suffix, level=messages.SUCCESS):
         if rows == 1:
-            prefix = _('1 {0} was'.format(self.model._meta.verbose_name))
+            prefix = _("1 {0} was".format(self.model._meta.verbose_name))
         else:  # pragma: nocover
             prefix = _(
-                '{0} {1} were'.format(rows, self.model._meta.verbose_name_plural)
+                "{0} {1} were".format(rows, self.model._meta.verbose_name_plural)
             )
-        self.message_user(request, '{0} {1}'.format(prefix, suffix), level=level)
+        self.message_user(request, "{0} {1}".format(prefix, suffix), level=level)
 
     @admin.action(
-        description=_('Update selected topologies (FETCH strategy only)'),
-        permissions=['change'],
+        description=_("Update selected topologies (FETCH strategy only)"),
+        permissions=["change"],
     )
     def update_selected(self, request, queryset):
         items = list(queryset)
         failed = []
         ignored = []
         for item in items:
-            if item.strategy == 'fetch':
+            if item.strategy == "fetch":
                 try:
                     item.update()
                 except Exception as e:
-                    failed.append('{0}: {1}'.format(item.label, str(e)))
-                    with log_failure('update topology admin action', item):
+                    failed.append("{0}: {1}".format(item.label, str(e)))
+                    with log_failure("update topology admin action", item):
                         raise e
             else:
                 ignored.append(item)
@@ -193,23 +193,23 @@ def update_selected(self, request, queryset):
         successes = len(items) - failures
         total_ignored = len(ignored)
         if successes > 0:
-            self._message(request, successes, _('successfully updated'))
+            self._message(request, successes, _("successfully updated"))
         if failures > 0:
-            message = _('not updated. %s') % '; '.join(failed)
+            message = _("not updated. %s") % "; ".join(failed)
             self._message(request, failures, message, level=messages.ERROR)
         if total_ignored > 0:
             message = _("ignored (not using FETCH strategy)")
             self._message(request, total_ignored, message, level=messages.WARNING)
 
-    @admin.action(description=_('Publish selected topologies'), permissions=['change'])
+    @admin.action(description=_("Publish selected topologies"), permissions=["change"])
     def publish_selected(self, request, queryset):
         rows_updated = queryset.update(published=True)
-        self._message(request, rows_updated, _('successfully published'))
+        self._message(request, rows_updated, _("successfully published"))
 
-    @admin.action(description=_('Unpublish selected items'), permissions=['change'])
+    @admin.action(description=_("Unpublish selected items"), permissions=["change"])
     def unpublish_selected(self, request, queryset):
         rows_updated = queryset.update(published=False)
-        self._message(request, rows_updated, _('successfully unpublished'))
+        self._message(request, rows_updated, _("successfully unpublished"))
 
     def visualize_view(self, request, pk):
         graph_url, history_url = self.get_graph_urls(request, pk)
@@ -217,20 +217,20 @@ def visualize_view(self, request, pk):
         opts = self.model._meta
         context.update(
             {
-                'is_popup': True,
-                'opts': opts,
-                'change': False,
-                'media': self.media,
-                'graph_url': graph_url,
-                'history_url': history_url,
+                "is_popup": True,
+                "opts": opts,
+                "change": False,
+                "media": self.media,
+                "graph_url": graph_url,
+                "history_url": history_url,
             }
         )
-        return TemplateResponse(request, 'admin/topology/visualize.html', context)
+        return TemplateResponse(request, "admin/topology/visualize.html", context)
 
 
 class UserPropertiesForm(forms.ModelForm):
     class Meta:
-        widgets = {'user_properties': FlatJsonWidget}
+        widgets = {"user_properties": FlatJsonWidget}
 
 
 class NodeLinkMixin(MultitenantAdminMixin):
@@ -239,69 +239,69 @@ class NodeLinkMixin(MultitenantAdminMixin):
     other extensions to override the admin queryset
     """
 
-    readonly_fields = ['readonly_properties']
+    readonly_fields = ["readonly_properties"]
 
     def get_fields(self, request, obj):
         fields = super().get_fields(request, obj)
         if obj:
             return fields
         fields_copy = list(fields)
-        fields_copy.remove('organization')
+        fields_copy.remove("organization")
         return fields_copy
 
     def get_queryset(self, request):
         return self.model.get_queryset(super().get_queryset(request))
 
     def readonly_properties(self, obj):
-        output = ''
+        output = ""
         for key, value in obj.properties.items():
-            key = key.replace('_', ' ').capitalize()
-            output += f'<p><strong>{key}</strong>: {value}</p>'
+            key = key.replace("_", " ").capitalize()
+            output += f"<p><strong>{key}</strong>: {value}</p>"
         return mark_safe(output)
 
-    readonly_properties.short_description = _('Properties')
+    readonly_properties.short_description = _("Properties")
 
 
 class TopologyFilter(MultitenantRelatedOrgFilter):
-    field_name = 'topology'
-    parameter_name = 'topology_id'
-    title = _('topology')
+    field_name = "topology"
+    parameter_name = "topology_id"
+    title = _("topology")
 
 
 @admin.register(Node)
 class NodeAdmin(NodeLinkMixin, BaseAdmin):
     model = Node
     form = UserPropertiesForm
-    change_form_template = 'admin/topology/node/change_form.html'
-    list_display = ['get_name', 'organization', 'topology', 'addresses']
-    search_fields = ['addresses', 'label', 'properties']
+    change_form_template = "admin/topology/node/change_form.html"
+    list_display = ["get_name", "organization", "topology", "addresses"]
+    search_fields = ["addresses", "label", "properties"]
     list_filter = [
         (MultitenantOrgFilter),
         (TopologyFilter),
     ]
-    multitenant_shared_relations = ('topology',)
-    autocomplete_fields = ('topology',)
+    multitenant_shared_relations = ("topology",)
+    autocomplete_fields = ("topology",)
     fields = [
-        'topology',
-        'organization',
-        'label',
-        'addresses',
-        'readonly_properties',
-        'user_properties',
-        'created',
-        'modified',
+        "topology",
+        "organization",
+        "label",
+        "addresses",
+        "readonly_properties",
+        "user_properties",
+        "created",
+        "modified",
     ]
 
-    def change_view(self, request, object_id, form_url='', extra_context=None):
+    def change_view(self, request, object_id, form_url="", extra_context=None):
         extra_context = extra_context or {}
         link_model = self.model.source_link_set.field.model
-        admin_url = 'admin:{0}_link_change'.format(self.opts.app_label)
+        admin_url = "admin:{0}_link_change".format(self.opts.app_label)
         extra_context.update(
             {
-                'node_links': link_model.objects.select_related('source', 'target')
-                .only('source__label', 'target__label', 'cost', 'status')
+                "node_links": link_model.objects.select_related("source", "target")
+                .only("source__label", "target__label", "cost", "status")
                 .filter(Q(source_id=object_id) | Q(target_id=object_id)),
-                'admin_url': admin_url,
+                "admin_url": admin_url,
             }
         )
         return super().change_view(request, object_id, form_url, extra_context)
@@ -311,39 +311,39 @@ def change_view(self, request, object_id, form_url='', extra_context=None):
 class LinkAdmin(NodeLinkMixin, BaseAdmin):
     model = Link
     form = UserPropertiesForm
-    raw_id_fields = ['source', 'target']
+    raw_id_fields = ["source", "target"]
     search_fields = [
-        'source__label',
-        'target__label',
-        'source__addresses',
-        'target__addresses',
-        'properties',
+        "source__label",
+        "target__label",
+        "source__addresses",
+        "target__addresses",
+        "properties",
     ]
     list_display = [
-        '__str__',
-        'organization',
-        'topology',
-        'status',
-        'cost',
-        'cost_text',
+        "__str__",
+        "organization",
+        "topology",
+        "status",
+        "cost",
+        "cost_text",
     ]
     list_filter = [
-        'status',
+        "status",
         (MultitenantOrgFilter),
         (TopologyFilter),
     ]
-    multitenant_shared_relations = ('topology', 'source', 'target')
-    autocomplete_fields = ('topology',)
+    multitenant_shared_relations = ("topology", "source", "target")
+    autocomplete_fields = ("topology",)
     fields = [
-        'topology',
-        'organization',
-        'status',
-        'source',
-        'target',
-        'cost',
-        'cost_text',
-        'readonly_properties',
-        'user_properties',
-        'created',
-        'modified',
+        "topology",
+        "organization",
+        "status",
+        "source",
+        "target",
+        "cost",
+        "cost_text",
+        "readonly_properties",
+        "user_properties",
+        "created",
+        "modified",
     ]
diff --git a/openwisp_network_topology/api/filters.py b/openwisp_network_topology/api/filters.py
index e77fdc14..c9a2159c 100644
--- a/openwisp_network_topology/api/filters.py
+++ b/openwisp_network_topology/api/filters.py
@@ -2,24 +2,24 @@
 
 from openwisp_users.api.filters import OrganizationManagedFilter
 
-Node = load_model('topology', 'Node')
-Link = load_model('topology', 'Link')
-Topology = load_model('topology', 'Topology')
+Node = load_model("topology", "Node")
+Link = load_model("topology", "Link")
+Topology = load_model("topology", "Topology")
 
 
 class NetworkCollectionFilter(OrganizationManagedFilter):
     class Meta(OrganizationManagedFilter.Meta):
         model = Topology
-        fields = OrganizationManagedFilter.Meta.fields + ['strategy', 'parser']
+        fields = OrganizationManagedFilter.Meta.fields + ["strategy", "parser"]
 
 
 class NodeFilter(OrganizationManagedFilter):
     class Meta(OrganizationManagedFilter.Meta):
         model = Node
-        fields = OrganizationManagedFilter.Meta.fields + ['topology']
+        fields = OrganizationManagedFilter.Meta.fields + ["topology"]
 
 
 class LinkFilter(OrganizationManagedFilter):
     class Meta(OrganizationManagedFilter.Meta):
         model = Link
-        fields = OrganizationManagedFilter.Meta.fields + ['topology', 'status']
+        fields = OrganizationManagedFilter.Meta.fields + ["topology", "status"]
diff --git a/openwisp_network_topology/api/parsers.py b/openwisp_network_topology/api/parsers.py
index 07d05e19..2dd90fb3 100644
--- a/openwisp_network_topology/api/parsers.py
+++ b/openwisp_network_topology/api/parsers.py
@@ -9,13 +9,13 @@ class TextParser(JSONParser):
     Dummy TextParser accepting any text (used in ReceiveTopologyView)
     """
 
-    media_type = 'text/plain'
+    media_type = "text/plain"
 
     def parse(self, stream, media_type=None, parser_context=None):
         parser_context = parser_context or {}
-        encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)
+        encoding = parser_context.get("encoding", settings.DEFAULT_CHARSET)
 
         try:
             return stream.read().decode(encoding)
         except ValidationError as e:  # pragma: nocover
-            raise ParseError('text/plain parse error - %s' % str(e))
+            raise ParseError("text/plain parse error - %s" % str(e))
diff --git a/openwisp_network_topology/api/serializers.py b/openwisp_network_topology/api/serializers.py
index 31ccebde..674552fe 100644
--- a/openwisp_network_topology/api/serializers.py
+++ b/openwisp_network_topology/api/serializers.py
@@ -8,9 +8,9 @@
 from openwisp_users.api.mixins import FilterSerializerByOrgManaged
 from openwisp_utils.api.serializers import ValidatedModelSerializer
 
-Node = swapper.load_model('topology', 'Node')
-Link = swapper.load_model('topology', 'Link')
-Topology = swapper.load_model('topology', 'Topology')
+Node = swapper.load_model("topology", "Node")
+Link = swapper.load_model("topology", "Link")
+Topology = swapper.load_model("topology", "Topology")
 
 
 class NetworkCollectionSerializer(serializers.ListSerializer):
@@ -25,15 +25,15 @@ def data(self):
     def to_representation(self, data):
         return OrderedDict(
             (
-                ('type', 'NetworkCollection'),
-                ('collection', super().to_representation(data)),
+                ("type", "NetworkCollection"),
+                ("collection", super().to_representation(data)),
             )
         )
 
 
 def get_receive_url(pk, key):
-    path = reverse('receive_topology', args=[pk])
-    url = '{0}?key={1}'.format(path, key)
+    path = reverse("receive_topology", args=[pk])
+    url = "{0}?key={1}".format(path, key)
     return url
 
 
@@ -50,24 +50,24 @@ def get_representation_data(obj):
         nodes.append(node.json(dict=True, original=False))
     netjson = OrderedDict(
         (
-            ('type', 'NetworkGraph'),
-            ('protocol', obj.protocol),
-            ('version', obj.version),
-            ('metric', obj.metric),
-            ('label', obj.label),
-            ('id', str(obj.id)),
-            ('parser', obj.parser),
-            ('organization', str(obj.organization.id) if obj.organization else None),
-            ('strategy', obj.strategy),
-            ('url', obj.url),
-            ('key', obj.key),
-            ('expiration_time', obj.expiration_time),
-            ('receive_url', get_receive_url(obj.pk, obj.key)),
-            ('published', obj.published),
-            ('created', obj.created),
-            ('modified', obj.modified),
-            ('nodes', nodes),
-            ('links', links),
+            ("type", "NetworkGraph"),
+            ("protocol", obj.protocol),
+            ("version", obj.version),
+            ("metric", obj.metric),
+            ("label", obj.label),
+            ("id", str(obj.id)),
+            ("parser", obj.parser),
+            ("organization", str(obj.organization.id) if obj.organization else None),
+            ("strategy", obj.strategy),
+            ("url", obj.url),
+            ("key", obj.key),
+            ("expiration_time", obj.expiration_time),
+            ("receive_url", get_receive_url(obj.pk, obj.key)),
+            ("published", obj.published),
+            ("created", obj.created),
+            ("modified", obj.modified),
+            ("nodes", nodes),
+            ("links", links),
         )
     )
     return netjson
@@ -80,8 +80,8 @@ def to_representation(self, obj):
         of Topology object.
         """
         topology_data = get_representation_data(obj)
-        topology_data['receive_url'] = self.context['request'].build_absolute_uri(
-            topology_data['receive_url']
+        topology_data["receive_url"] = self.context["request"].build_absolute_uri(
+            topology_data["receive_url"]
         )
         return topology_data
 
@@ -89,7 +89,7 @@ def to_representation(self, obj):
 class TopologySerializer(NetworkGraphRepresentation, ValidatedModelSerializer):
     class Meta:
         model = Topology
-        fields = '__all__'
+        fields = "__all__"
 
 
 class BaseSerializer(FilterSerializerByOrgManaged, ValidatedModelSerializer):
@@ -102,9 +102,9 @@ class NetworkGraphSerializer(BaseSerializer):
     """
 
     def to_representation(self, obj):
-        if self.context['request'].method == 'POST':
+        if self.context["request"].method == "POST":
             serializer = TopologySerializer(
-                self.instance, context={'request': self.context['request']}
+                self.instance, context={"request": self.context["request"]}
             )
             return serializer.data
         return obj.json(dict=True)
@@ -112,44 +112,44 @@ def to_representation(self, obj):
     class Meta:
         model = Topology
         fields = (
-            'label',
-            'organization',
-            'parser',
-            'strategy',
-            'key',
-            'expiration_time',
-            'url',
-            'published',
+            "label",
+            "organization",
+            "parser",
+            "strategy",
+            "key",
+            "expiration_time",
+            "url",
+            "published",
         )
         list_serializer_class = NetworkCollectionSerializer
-        extra_kwargs = {'published': {'initial': True}}
+        extra_kwargs = {"published": {"initial": True}}
 
 
 class NetworkGraphUpdateSerializer(NetworkGraphRepresentation, BaseSerializer):
     class Meta:
         model = Topology
         fields = (
-            'label',
-            'organization',
-            'parser',
-            'strategy',
-            'key',
-            'expiration_time',
-            'url',
-            'published',
+            "label",
+            "organization",
+            "parser",
+            "strategy",
+            "key",
+            "expiration_time",
+            "url",
+            "published",
         )
 
     def validate_strategy(self, value):
-        if value == 'receive' and not self.initial_data.get('key'):
+        if value == "receive" and not self.initial_data.get("key"):
             raise serializers.ValidationError(
-                _('A key must be specified when using RECEIVE strategy')
+                _("A key must be specified when using RECEIVE strategy")
             )
         return value
 
     def validate_url(self, value):
-        if not value and self.initial_data.get('strategy') == 'fetch':
+        if not value and self.initial_data.get("strategy") == "fetch":
             raise serializers.ValidationError(
-                _('An url must be specified when using FETCH strategy')
+                _("An url must be specified when using FETCH strategy")
             )
         return value
 
@@ -160,20 +160,20 @@ class BaseNodeLinkSerializer(BaseSerializer):
     def validate(self, data):
         instance = self.instance or self.Meta.model(**data)
         instance.full_clean()
-        data['organization'] = instance.organization
+        data["organization"] = instance.organization
         return data
 
     def validate_properties(self, value):
         if type(value) is not dict:
             raise serializers.ValidationError(
-                _('Value must be valid JSON or key, valued pair.')
+                _("Value must be valid JSON or key, valued pair.")
             )
         return value
 
     def validate_user_properties(self, value):
         if type(value) is not dict:
             raise serializers.ValidationError(
-                _('Value must be valid JSON or key, valued pair.')
+                _("Value must be valid JSON or key, valued pair.")
             )
         return value
 
@@ -185,39 +185,39 @@ class NodeSerializer(BaseNodeLinkSerializer):
     class Meta:
         model = Node
         fields = (
-            'id',
-            'topology',
-            'organization',
-            'label',
-            'addresses',
-            'properties',
-            'user_properties',
-            'created',
-            'modified',
+            "id",
+            "topology",
+            "organization",
+            "label",
+            "addresses",
+            "properties",
+            "user_properties",
+            "created",
+            "modified",
         )
-        read_only_fields = ('created', 'modified')
+        read_only_fields = ("created", "modified")
 
 
 class LinkSerializer(BaseNodeLinkSerializer):
     user_properties = serializers.JSONField(
         initial={},
-        help_text=_('If you need to add additional data to this link use this field'),
+        help_text=_("If you need to add additional data to this link use this field"),
     )
 
     class Meta:
         model = Link
         fields = (
-            'id',
-            'topology',
-            'organization',
-            'status',
-            'source',
-            'target',
-            'cost',
-            'cost_text',
-            'properties',
-            'user_properties',
-            'created',
-            'modified',
+            "id",
+            "topology",
+            "organization",
+            "status",
+            "source",
+            "target",
+            "cost",
+            "cost_text",
+            "properties",
+            "user_properties",
+            "created",
+            "modified",
         )
-        read_only_fields = ('organization', 'created', 'modified')
+        read_only_fields = ("organization", "created", "modified")
diff --git a/openwisp_network_topology/api/views.py b/openwisp_network_topology/api/views.py
index d61acbbd..58f786b7 100644
--- a/openwisp_network_topology/api/views.py
+++ b/openwisp_network_topology/api/views.py
@@ -28,10 +28,10 @@
 )
 
 logger = logging.getLogger(__name__)
-Snapshot = swapper.load_model('topology', 'Snapshot')
-Topology = swapper.load_model('topology', 'Topology')
-Node = swapper.load_model('topology', 'Node')
-Link = swapper.load_model('topology', 'Link')
+Snapshot = swapper.load_model("topology", "Snapshot")
+Topology = swapper.load_model("topology", "Topology")
+Node = swapper.load_model("topology", "Node")
+Link = swapper.load_model("topology", "Link")
 
 
 class RequireAuthentication(APIView):
@@ -50,14 +50,14 @@ class RequireAuthentication(APIView):
 
 class ListViewPagination(pagination.PageNumberPagination):
     page_size = 10
-    page_size_query_param = 'page_size'
+    page_size_query_param = "page_size"
     max_page_size = 100
 
 
 class UnpublishedTopologyFilterMixin:
     def get_queryset(self):
         qs = super().get_queryset()
-        if self.request.query_params.get('include_unpublished'):
+        if self.request.query_params.get("include_unpublished"):
             return qs
         return qs.filter(published=True)
 
@@ -74,7 +74,7 @@ class NetworkCollectionView(
     """
 
     serializer_class = NetworkGraphSerializer
-    queryset = Topology.objects.select_related('organization')
+    queryset = Topology.objects.select_related("organization")
     filter_backends = (DjangoFilterBackend,)
     filterset_class = NetworkCollectionFilter
 
@@ -102,7 +102,7 @@ class NetworkGraphView(
     """
 
     serializer_class = NetworkGraphUpdateSerializer
-    queryset = Topology.objects.select_related('organization')
+    queryset = Topology.objects.select_related("organization")
 
 
 class ReceiveTopologyView(APIView):
@@ -118,24 +118,24 @@ class ReceiveTopologyView(APIView):
     parser_classes = (TextParser,)
 
     def _validate_request(self, request, topology):
-        key = request.query_params.get('key')
+        key = request.query_params.get("key")
         # wrong content type: 415
-        if request.content_type != 'text/plain':
+        if request.content_type != "text/plain":
             return Response(
-                {'detail': _('expected content type "text/plain"')}, status=415
+                {"detail": _('expected content type "text/plain"')}, status=415
             )
         # missing key: 400
         if not key:
             return Response(
-                {'detail': _('missing required "key" parameter')}, status=400
+                {"detail": _('missing required "key" parameter')}, status=400
             )
         # wrong key 403
         if topology.key != key:
-            return Response({'detail': _('wrong key')}, status=403)
+            return Response({"detail": _("wrong key")}, status=403)
         return
 
     def post(self, request, pk, format=None):
-        topology = get_object_or_404(self.model, pk, strategy='receive')
+        topology = get_object_or_404(self.model, pk, strategy="receive")
         validation_response = self._validate_request(request, topology)
         if validation_response:
             return validation_response
@@ -143,13 +143,13 @@ def post(self, request, pk, format=None):
             topology.receive(request.data)
         except NetdiffException as e:
             error = _(
-                'Supplied data not recognized as %s, '
+                "Supplied data not recognized as %s, "
                 'got exception of type "%s" '
                 'with message "%s"'
             ) % (topology.get_parser_display(), e.__class__.__name__, e)
-            return Response({'detail': error}, status=400)
-        success_message = _('data received successfully')
-        return Response({'detail': success_message})
+            return Response({"detail": error}, status=400)
+        success_message = _("data received successfully")
+        return Response({"detail": success_message})
 
 
 class NetworkGraphHistoryView(RequireAuthentication):
@@ -165,28 +165,28 @@ class NetworkGraphHistoryView(RequireAuthentication):
     def get(self, request, pk, format=None):
         topology = get_object_or_404(self.topology_model, pk)
         self.check_object_permissions(request, topology)
-        date = request.query_params.get('date')
+        date = request.query_params.get("date")
         options = dict(topology=topology, date=date)
         # missing date: 400
         if not date:
             return Response(
-                {'detail': _('missing required "date" parameter')}, status=400
+                {"detail": _('missing required "date" parameter')}, status=400
             )
         try:
             s = self.snapshot_model.objects.get(**options)
             return Response(json.loads(s.data))
         except self.snapshot_model.DoesNotExist:
             return Response(
-                {'detail': _('no snapshot found for this date')}, status=404
+                {"detail": _("no snapshot found for this date")}, status=404
             )
         except ValidationError:
-            return Response({'detail': _('invalid date supplied')}, status=403)
+            return Response({"detail": _("invalid date supplied")}, status=403)
 
 
 class NodeListCreateView(
     ProtectedAPIMixin, FilterByOrganizationManaged, generics.ListCreateAPIView
 ):
-    queryset = Node.objects.order_by('-created')
+    queryset = Node.objects.order_by("-created")
     serializer_class = NodeSerializer
     pagination_class = ListViewPagination
     filter_backends = (DjangoFilterBackend,)
@@ -198,7 +198,7 @@ class NodeDetailView(
     FilterByOrganizationManaged,
     generics.RetrieveUpdateDestroyAPIView,
 ):
-    queryset = Node.objects.all().select_related('topology')
+    queryset = Node.objects.all().select_related("topology")
     serializer_class = NodeSerializer
 
 
@@ -206,10 +206,10 @@ class LinkListCreateView(
     ProtectedAPIMixin, FilterByOrganizationManaged, generics.ListCreateAPIView
 ):
     queryset = Link.objects.select_related(
-        'topology',
-        'source',
-        'target',
-    ).order_by('-created')
+        "topology",
+        "source",
+        "target",
+    ).order_by("-created")
     serializer_class = LinkSerializer
     pagination_class = ListViewPagination
     filter_backends = (DjangoFilterBackend,)
@@ -222,9 +222,9 @@ class LinkDetailView(
     generics.RetrieveUpdateDestroyAPIView,
 ):
     queryset = Link.objects.select_related(
-        'topology',
-        'source',
-        'target',
+        "topology",
+        "source",
+        "target",
     )
     serializer_class = LinkSerializer
 
diff --git a/openwisp_network_topology/apps.py b/openwisp_network_topology/apps.py
index fbe5c1af..bf919234 100644
--- a/openwisp_network_topology/apps.py
+++ b/openwisp_network_topology/apps.py
@@ -8,9 +8,9 @@
 
 
 class OpenwispNetworkTopologyConfig(AppConfig):
-    name = 'openwisp_network_topology'
-    label = 'topology'
-    verbose_name = _('Network Topology')
+    name = "openwisp_network_topology"
+    label = "topology"
+    verbose_name = _("Network Topology")
 
     def ready(self, *args, **kwargs):
         if SIGNALS:  # pragma: nocover
@@ -24,27 +24,27 @@ def register_menu_groups(self):
         register_menu_group(
             position=110,
             config={
-                'label': 'Network Topology',
-                'items': {
+                "label": "Network Topology",
+                "items": {
                     1: {
-                        'label': _('Topologies'),
-                        'model': get_model_name('topology', 'Topology'),
-                        'name': 'changelist',
-                        'icon': 'ow-topology',
+                        "label": _("Topologies"),
+                        "model": get_model_name("topology", "Topology"),
+                        "name": "changelist",
+                        "icon": "ow-topology",
                     },
                     2: {
-                        'label': _('Nodes'),
-                        'model': get_model_name('topology', 'Node'),
-                        'name': 'changelist',
-                        'icon': 'ow-node',
+                        "label": _("Nodes"),
+                        "model": get_model_name("topology", "Node"),
+                        "name": "changelist",
+                        "icon": "ow-node",
                     },
                     3: {
-                        'label': _('Links'),
-                        'model': get_model_name('topology', 'Link'),
-                        'name': 'changelist',
-                        'icon': 'ow-link',
+                        "label": _("Links"),
+                        "model": get_model_name("topology", "Link"),
+                        "name": "changelist",
+                        "icon": "ow-link",
                     },
                 },
-                'icon': 'ow-network-topology',
+                "icon": "ow-network-topology",
             },
         )
diff --git a/openwisp_network_topology/base/link.py b/openwisp_network_topology/base/link.py
index fb6ef4f1..addc7bd0 100644
--- a/openwisp_network_topology/base/link.py
+++ b/openwisp_network_topology/base/link.py
@@ -29,35 +29,35 @@ class AbstractLink(ShareableOrgMixin, TimeStampedEditableModel):
     """
 
     topology = models.ForeignKey(
-        swapper.get_model_name('topology', 'Topology'), on_delete=models.CASCADE
+        swapper.get_model_name("topology", "Topology"), on_delete=models.CASCADE
     )
     source = models.ForeignKey(
-        swapper.get_model_name('topology', 'Node'),
-        related_name='source_link_set',
+        swapper.get_model_name("topology", "Node"),
+        related_name="source_link_set",
         on_delete=models.CASCADE,
     )
     target = models.ForeignKey(
-        swapper.get_model_name('topology', 'Node'),
-        related_name='target_link_set',
+        swapper.get_model_name("topology", "Node"),
+        related_name="target_link_set",
         on_delete=models.CASCADE,
     )
     cost = models.FloatField()
     cost_text = models.CharField(max_length=24, blank=True)
-    STATUS = Choices('up', 'down')
+    STATUS = Choices("up", "down")
     status = StatusField()
     properties = JSONField(
         default=dict,
         blank=True,
-        load_kwargs={'object_pairs_hook': OrderedDict},
-        dump_kwargs={'indent': 4, 'cls': JSONEncoder},
+        load_kwargs={"object_pairs_hook": OrderedDict},
+        dump_kwargs={"indent": 4, "cls": JSONEncoder},
     )
     user_properties = JSONField(
-        verbose_name=_('user defined properties'),
-        help_text=_('If you need to add additional data to this link use this field'),
+        verbose_name=_("user defined properties"),
+        help_text=_("If you need to add additional data to this link use this field"),
         default=dict,
         blank=True,
-        load_kwargs={'object_pairs_hook': OrderedDict},
-        dump_kwargs={'indent': 4, 'cls': JSONEncoder},
+        load_kwargs={"object_pairs_hook": OrderedDict},
+        dump_kwargs={"indent": 4, "cls": JSONEncoder},
     )
     status_changed = models.DateTimeField(auto_now=True)
 
@@ -76,7 +76,7 @@ def save(self, *args, **kwargs):
         self._initial_status = self.status
 
     def __str__(self):
-        return '{0} - {1}'.format(self.source.get_name(), self.target.get_name())
+        return "{0} - {1}".format(self.source.get_name(), self.target.get_name())
 
     def full_clean(self, *args, **kwargs):
         self.validate_organization()
@@ -85,20 +85,20 @@ def full_clean(self, *args, **kwargs):
 
     def clean(self):
         if self.source == self.target or self.source_id == self.target_id:
-            raise ValidationError(_('source and target must not be the same'))
+            raise ValidationError(_("source and target must not be the same"))
         if self.properties is None:
             self.properties = {}
         # these properties are auto-generated and should not be saved
-        for attr in ['status', 'status_changed', 'modified', 'created']:
+        for attr in ["status", "status_changed", "modified", "created"]:
             if attr in self.properties:
                 del self.properties[attr]
 
     def validate_topology(self):
         errors = {}
         if self.source.topology_id != self.topology_id:
-            errors['source'] = _('Source node and link should have same topology.')
+            errors["source"] = _("Source node and link should have same topology.")
         if self.target.topology_id != self.topology_id:
-            errors['target'] = _('Target node and link should have same topology.')
+            errors["target"] = _("Target node and link should have same topology.")
         if errors:
             raise ValidationError(errors)
 
@@ -115,16 +115,16 @@ def validate_organization(self):
             if self.source.organization_id != self.topology.organization_id:
                 errors.update(
                     {
-                        'source': _(
-                            'Source node and topology should have same organization.'
+                        "source": _(
+                            "Source node and topology should have same organization."
                         )
                     }
                 )
             if self.target.organization_id != self.topology.organization_id:
                 errors.update(
                     {
-                        'target': _(
-                            'Target node and topology should have same organization.'
+                        "target": _(
+                            "Target node and topology should have same organization."
                         )
                     }
                 )
@@ -142,10 +142,10 @@ def json(self, dict=False, original=False, **kwargs):
         """
         netjson = OrderedDict(
             (
-                ('source', self.source.netjson_id),
-                ('target', self.target.netjson_id),
-                ('cost', self.cost),
-                ('cost_text', self.cost_text or ''),
+                ("source", self.source.netjson_id),
+                ("target", self.target.netjson_id),
+                ("cost", self.cost),
+                ("cost_text", self.cost_text or ""),
             )
         )
         # properties contain status by default
@@ -154,11 +154,11 @@ def json(self, dict=False, original=False, **kwargs):
             properties.update(self.properties)
         if not original:
             properties.update(self.user_properties)
-            properties['status'] = self.status
-            properties['status_changed'] = self.status_changed
-            properties['created'] = self.created
-            properties['modified'] = self.modified
-        netjson['properties'] = properties
+            properties["status"] = self.status
+            properties["status_changed"] = self.status_changed
+            properties["created"] = self.created
+            properties["modified"] = self.modified
+        netjson["properties"] = properties
         if dict:
             return netjson
         return json.dumps(netjson, cls=JSONEncoder, **kwargs)
@@ -195,21 +195,21 @@ def delete_expired_links(cls):
         if LINK_EXPIRATION not in [False, None]:
             expiration_date = now() - timedelta(days=int(LINK_EXPIRATION))
             expired_links = cls.objects.filter(
-                status='down', modified__lt=expiration_date
+                status="down", modified__lt=expiration_date
             )
             expired_links_length = len(expired_links)
             if expired_links_length:
-                print_info('Deleting {0} expired links'.format(expired_links_length))
+                print_info("Deleting {0} expired links".format(expired_links_length))
                 for link in expired_links:
                     link.delete()
 
     @classmethod
     def get_queryset(cls, qs):
         """admin list queryset"""
-        return qs.select_related('organization', 'topology', 'source', 'target')
+        return qs.select_related("organization", "topology", "source", "target")
 
 
-@receiver(post_save, sender=swapper.get_model_name('topology', 'Link'))
-@receiver(post_delete, sender=swapper.get_model_name('topology', 'Link'))
+@receiver(post_save, sender=swapper.get_model_name("topology", "Link"))
+@receiver(post_delete, sender=swapper.get_model_name("topology", "Link"))
 def send_topology_signal(sender, instance, **kwargs):
     update_topology.send(sender=sender, topology=instance.topology)
diff --git a/openwisp_network_topology/base/node.py b/openwisp_network_topology/base/node.py
index 15a52551..483e9edd 100644
--- a/openwisp_network_topology/base/node.py
+++ b/openwisp_network_topology/base/node.py
@@ -28,7 +28,7 @@ class AbstractNode(ShareableOrgMixin, TimeStampedEditableModel):
     """
 
     topology = models.ForeignKey(
-        swapper.get_model_name('topology', 'Topology'), on_delete=models.CASCADE
+        swapper.get_model_name("topology", "Topology"), on_delete=models.CASCADE
     )
     label = models.CharField(max_length=64, blank=True)
     # netjson ID and local_addresses
@@ -36,16 +36,16 @@ class AbstractNode(ShareableOrgMixin, TimeStampedEditableModel):
     properties = JSONField(
         default=dict,
         blank=True,
-        load_kwargs={'object_pairs_hook': OrderedDict},
-        dump_kwargs={'indent': 4, 'cls': JSONEncoder},
+        load_kwargs={"object_pairs_hook": OrderedDict},
+        dump_kwargs={"indent": 4, "cls": JSONEncoder},
     )
     user_properties = JSONField(
-        verbose_name=_('user defined properties'),
-        help_text=_('If you need to add additional data to this node use this field'),
+        verbose_name=_("user defined properties"),
+        help_text=_("If you need to add additional data to this node use this field"),
         default=dict,
         blank=True,
-        load_kwargs={'object_pairs_hook': OrderedDict},
-        dump_kwargs={'indent': 4, 'cls': JSONEncoder},
+        load_kwargs={"object_pairs_hook": OrderedDict},
+        dump_kwargs={"indent": 4, "cls": JSONEncoder},
     )
 
     class Meta:
@@ -77,7 +77,7 @@ def local_addresses(self):
 
     @property
     def name(self):
-        return self.label or self.netjson_id or ''
+        return self.label or self.netjson_id or ""
 
     def get_name(self):
         """
@@ -102,7 +102,7 @@ def get_organization_id(self):
                 and self.topology.organization_id != self.organization_id
             ):
                 raise ValidationError(
-                    _('node should have same organization as topology.')
+                    _("node should have same organization as topology.")
                 )
             return self.organization_id
 
@@ -114,18 +114,18 @@ def json(self, dict=False, original=False, **kwargs):
         as it has been collected from the network (used when
         doing the comparison).
         """
-        netjson = OrderedDict({'id': self.netjson_id})
+        netjson = OrderedDict({"id": self.netjson_id})
         label = self.get_name()
         if label:
-            netjson['label'] = label
-        for attr in ['local_addresses', 'properties']:
+            netjson["label"] = label
+        for attr in ["local_addresses", "properties"]:
             value = getattr(self, attr)
-            if value or attr == 'properties':
+            if value or attr == "properties":
                 netjson[attr] = deepcopy(value)
         if not original:
-            netjson['properties'].update(deepcopy(self.user_properties))
-            netjson['properties']['created'] = JSONEncoder().default(self.created)
-            netjson['properties']['modified'] = JSONEncoder().default(self.modified)
+            netjson["properties"].update(deepcopy(self.user_properties))
+            netjson["properties"]["created"] = JSONEncoder().default(self.created)
+            netjson["properties"]["modified"] = JSONEncoder().default(self.modified)
         if dict:
             return netjson
         return json.dumps(netjson, cls=JSONEncoder, **kwargs)
@@ -177,17 +177,17 @@ def delete_expired_nodes(cls):
             )
             expired_nodes_length = len(expired_nodes)
             if expired_nodes_length:
-                print_info('Deleting {0} expired nodes'.format(expired_nodes_length))
+                print_info("Deleting {0} expired nodes".format(expired_nodes_length))
                 for node in expired_nodes:
                     node.delete()
 
     @classmethod
     def get_queryset(cls, qs):
         """admin list queryset"""
-        return qs.select_related('organization', 'topology')
+        return qs.select_related("organization", "topology")
 
 
-@receiver(post_save, sender=swapper.get_model_name('topology', 'Node'))
-@receiver(post_delete, sender=swapper.get_model_name('topology', 'Node'))
+@receiver(post_save, sender=swapper.get_model_name("topology", "Node"))
+@receiver(post_delete, sender=swapper.get_model_name("topology", "Node"))
 def send_topology_signal(sender, instance, **kwargs):
     update_topology.send(sender=sender, topology=instance.topology)
diff --git a/openwisp_network_topology/base/snapshot.py b/openwisp_network_topology/base/snapshot.py
index ed5ae879..1db9a9b2 100644
--- a/openwisp_network_topology/base/snapshot.py
+++ b/openwisp_network_topology/base/snapshot.py
@@ -11,13 +11,13 @@ class AbstractSnapshot(TimeStampedEditableModel):
     """
 
     topology = models.ForeignKey(
-        swapper.get_model_name('topology', 'Topology'), on_delete=models.CASCADE
+        swapper.get_model_name("topology", "Topology"), on_delete=models.CASCADE
     )
     data = models.TextField(blank=False)
     date = models.DateField(auto_now=True)
 
     class Meta:
-        verbose_name_plural = _('snapshots')
+        verbose_name_plural = _("snapshots")
         abstract = True
 
     def __str__(self):
diff --git a/openwisp_network_topology/base/topology.py b/openwisp_network_topology/base/topology.py
index 65038dd2..6a0cd6cf 100644
--- a/openwisp_network_topology/base/topology.py
+++ b/openwisp_network_topology/base/topology.py
@@ -24,79 +24,79 @@
 from ..tasks import handle_update_topology
 from ..utils import print_info
 
-STRATEGIES = (('fetch', _('FETCH')), ('receive', _('RECEIVE')))
+STRATEGIES = (("fetch", _("FETCH")), ("receive", _("RECEIVE")))
 
 
 class AbstractTopology(ShareableOrgMixin, TimeStampedEditableModel):
-    label = models.CharField(_('label'), max_length=64)
+    label = models.CharField(_("label"), max_length=64)
     parser = models.CharField(
-        _('format'),
+        _("format"),
         choices=PARSERS,
         max_length=128,
-        help_text=_('Select topology format'),
+        help_text=_("Select topology format"),
     )
     strategy = models.CharField(
-        _('strategy'), max_length=16, choices=STRATEGIES, default='fetch', db_index=True
+        _("strategy"), max_length=16, choices=STRATEGIES, default="fetch", db_index=True
     )
     # fetch strategy
     url = models.URLField(
-        _('url'),
+        _("url"),
         blank=True,
-        help_text=_('Topology data will be fetched from this URL' ' (FETCH strategy)'),
+        help_text=_("Topology data will be fetched from this URL" " (FETCH strategy)"),
     )
     # receive strategy
     key = KeyField(
         unique=False,
         db_index=False,
-        help_text=_('key needed to update topology from nodes '),
-        verbose_name=_('key'),
+        help_text=_("key needed to update topology from nodes "),
+        verbose_name=_("key"),
         blank=True,
     )
     # receive strategy
     expiration_time = models.PositiveIntegerField(
-        _('expiration time'),
+        _("expiration time"),
         default=0,
         help_text=_(
             '"Expiration Time" in seconds: setting this to 0 will immediately mark missing links '
-            'as down; a value higher than 0 will delay marking missing links as down until the '
+            "as down; a value higher than 0 will delay marking missing links as down until the "
             '"modified" field of a link is older than "Expiration Time"'
         ),
     )
     published = models.BooleanField(
-        _('published'),
+        _("published"),
         default=True,
         help_text=_(
-            'Unpublished topologies won\'t be updated or ' 'shown in the visualizer'
+            "Unpublished topologies won't be updated or " "shown in the visualizer"
         ),
     )
 
     # the following fields will be filled automatically
-    protocol = models.CharField(_('protocol'), max_length=64, blank=True)
-    version = models.CharField(_('version'), max_length=24, blank=True)
-    revision = models.CharField(_('revision'), max_length=64, blank=True)
-    metric = models.CharField(_('metric'), max_length=24, blank=True)
+    protocol = models.CharField(_("protocol"), max_length=64, blank=True)
+    version = models.CharField(_("version"), max_length=24, blank=True)
+    revision = models.CharField(_("revision"), max_length=64, blank=True)
+    metric = models.CharField(_("metric"), max_length=24, blank=True)
 
-    status = {'added': 'up', 'removed': 'down', 'changed': 'up'}
-    action = {'added': 'add', 'changed': 'change', 'removed': 'remove'}
+    status = {"added": "up", "removed": "down", "changed": "up"}
+    action = {"added": "add", "changed": "change", "removed": "remove"}
 
     class Meta:
-        verbose_name_plural = _('topologies')
+        verbose_name_plural = _("topologies")
         abstract = True
 
     def __str__(self):
-        return '{0} - {1}'.format(self.label, self.get_parser_display())
+        return "{0} - {1}".format(self.label, self.get_parser_display())
 
     def get_absolute_url(self):
-        return reverse('topology_detail', args=[self.pk])
+        return reverse("topology_detail", args=[self.pk])
 
     def clean(self):
-        if self.strategy == 'fetch' and not self.url:
+        if self.strategy == "fetch" and not self.url:
             raise ValidationError(
-                {'url': [_('an url must be specified when using FETCH strategy')]}
+                {"url": [_("an url must be specified when using FETCH strategy")]}
             )
-        elif self.strategy == 'receive' and not self.key:
+        elif self.strategy == "receive" and not self.key:
             raise ValidationError(
-                {'key': [_('a key must be specified when using RECEIVE strategy')]}
+                {"key": [_("a key must be specified when using RECEIVE strategy")]}
             )
 
     @cached_property
@@ -123,7 +123,7 @@ def get_topology_data(self, data=None):
         latest = self.parser_class(data=data, url=self.url, timeout=TIMEOUT)
         # update topology attributes if needed
         changed = False
-        for attr in ['protocol', 'version', 'metric']:
+        for attr in ["protocol", "version", "metric"]:
             latest_attr = getattr(latest, attr)
             if getattr(self, attr) != latest_attr:
                 setattr(self, attr, latest_attr)
@@ -147,7 +147,7 @@ def get_nodes_queryset(self):
         return self.node_set.all()
 
     def get_links_queryset(self):
-        return self.link_set.select_related('source', 'target')
+        return self.link_set.select_related("source", "target")
 
     def json(self, dict=False, omit_down=False, original=False, **kwargs):
         """returns a dict that represents a NetJSON NetworkGraph object"""
@@ -156,7 +156,7 @@ def json(self, dict=False, omit_down=False, original=False, **kwargs):
         links_queryset = self.get_links_queryset()
         # needed to detect links coming back online
         if omit_down:
-            links_queryset = links_queryset.filter(status='up')
+            links_queryset = links_queryset.filter(status="up")
         # populate graph
         for link in links_queryset:
             links.append(link.json(dict=True, original=original))
@@ -164,17 +164,17 @@ def json(self, dict=False, omit_down=False, original=False, **kwargs):
             nodes.append(node.json(dict=True, original=original))
         netjson = OrderedDict(
             (
-                ('type', 'NetworkGraph'),
-                ('protocol', self.protocol),
-                ('version', self.version),
-                ('metric', self.metric),
-                ('label', self.label),
-                ('id', str(self.id)),
-                ('parser', self.parser),
-                ('created', self.created),
-                ('modified', self.modified),
-                ('nodes', nodes),
-                ('links', links),
+                ("type", "NetworkGraph"),
+                ("protocol", self.protocol),
+                ("version", self.version),
+                ("metric", self.metric),
+                ("label", self.label),
+                ("id", str(self.id)),
+                ("parser", self.parser),
+                ("created", self.created),
+                ("modified", self.modified),
+                ("nodes", nodes),
+                ("links", links),
             )
         )
         if dict:
@@ -196,40 +196,40 @@ def _create_link(self, **kwargs):
     def _update_added_items(self, items):
         Link, Node = self.link_model, self.node_model
 
-        for node_dict in items.get('nodes', []):
+        for node_dict in items.get("nodes", []):
             # if node exists, update its properties
-            node = Node.get_from_address(node_dict['id'], topology=self)
+            node = Node.get_from_address(node_dict["id"], topology=self)
             if node:
-                self._update_node_properties(node, node_dict, section='added')
+                self._update_node_properties(node, node_dict, section="added")
                 continue
             # if node doesn't exist create new
-            addresses = [node_dict['id']]
-            addresses += node_dict.get('local_addresses', [])
-            label = node_dict.get('label', '')
-            properties = node_dict.get('properties', {})
+            addresses = [node_dict["id"]]
+            addresses += node_dict.get("local_addresses", [])
+            label = node_dict.get("label", "")
+            properties = node_dict.get("properties", {})
             node = self._create_node(
                 label=label, addresses=addresses, properties=properties
             )
             node.full_clean()
             node.save()
 
-        for link_dict in items.get('links', []):
+        for link_dict in items.get("links", []):
             link = Link.get_from_nodes(
-                link_dict['source'], link_dict['target'], topology=self
+                link_dict["source"], link_dict["target"], topology=self
             )
             # if link exists, update its properties
             if link:
-                self._update_link_properties(link, link_dict, section='added')
+                self._update_link_properties(link, link_dict, section="added")
                 continue
             # if link does not exist create new
-            source = Node.get_from_address(link_dict['source'], self)
-            target = Node.get_from_address(link_dict['target'], self)
+            source = Node.get_from_address(link_dict["source"], self)
+            target = Node.get_from_address(link_dict["target"], self)
             link = self._create_link(
                 source=source,
                 target=target,
-                cost=link_dict['cost'],
-                cost_text=link_dict['cost_text'],
-                properties=link_dict['properties'],
+                cost=link_dict["cost"],
+                cost_text=link_dict["cost_text"],
+                properties=link_dict["properties"],
                 topology=self,
             )
             link.full_clean()
@@ -237,18 +237,18 @@ def _update_added_items(self, items):
 
     def _update_node_properties(self, node, node_dict, section):
         changed = False
-        if node.label != node_dict.get('label'):
+        if node.label != node_dict.get("label"):
             changed = True
-            node.label = node_dict.get('label')
-        local_addresses = node_dict.get('local_addresses')
+            node.label = node_dict.get("label")
+        local_addresses = node_dict.get("local_addresses")
         if node.addresses != local_addresses:
             changed = True
-            node.addresses = [node_dict['id']]
+            node.addresses = [node_dict["id"]]
             if local_addresses:
                 node.addresses += local_addresses
-        if node.properties != node_dict.get('properties'):
+        if node.properties != node_dict.get("properties"):
             changed = True
-            node.properties = node_dict.get('properties')
+            node.properties = node_dict.get("properties")
         # perform writes only if needed
         if changed:
             with log_failure(self.action[section], node):
@@ -261,14 +261,14 @@ def _update_link_properties(self, link, link_dict, section):
         if self.link_status_changed(link, self.status[section]):
             link.status = self.status[section]
             changed = True
-        if link.cost != link_dict.get('cost'):
-            link.cost = link_dict.get('cost')
+        if link.cost != link_dict.get("cost"):
+            link.cost = link_dict.get("cost")
             changed = True
-        if link.cost_text != link_dict.get('cost_text'):
-            link.cost_text = link_dict.get('cost_text')
+        if link.cost_text != link_dict.get("cost_text"):
+            link.cost_text = link_dict.get("cost_text")
             changed = True
-        if link.properties != link_dict.get('properties'):
-            link.properties = link_dict.get('properties')
+        if link.properties != link_dict.get("properties"):
+            link.properties = link_dict.get("properties")
             changed = True
         # perform writes only if needed
         if changed:
@@ -276,33 +276,33 @@ def _update_link_properties(self, link, link_dict, section):
                 link.full_clean()
                 link.save()
 
-    def _update_changed_items(self, items, section='changed'):
+    def _update_changed_items(self, items, section="changed"):
         Link, Node = self.link_model, self.node_model
-        for node_dict in items.get('nodes', []):
-            node = Node.get_from_address(node_dict['id'], topology=self)
+        for node_dict in items.get("nodes", []):
+            node = Node.get_from_address(node_dict["id"], topology=self)
             if node:
                 self._update_node_properties(node, node_dict, section=section)
 
-        for link_dict in items.get('links', []):
+        for link_dict in items.get("links", []):
             link = Link.get_from_nodes(
-                link_dict['source'], link_dict['target'], topology=self
+                link_dict["source"], link_dict["target"], topology=self
             )
             if link:
                 self._update_link_properties(link, link_dict, section=section)
 
     def update_topology(self, diff):
-        if diff['added']:
-            self._update_added_items(diff['added'])
-        if diff['changed']:
-            self._update_changed_items(diff['changed'])
-        if diff['removed']:
+        if diff["added"]:
+            self._update_added_items(diff["added"])
+        if diff["changed"]:
+            self._update_changed_items(diff["changed"])
+        if diff["removed"]:
             Link = self.link_model
-            for link_dict in diff['removed'].get('links', []):
+            for link_dict in diff["removed"].get("links", []):
                 link = Link.get_from_nodes(
-                    link_dict['source'], link_dict['target'], topology=self
+                    link_dict["source"], link_dict["target"], topology=self
                 )
                 if link:
-                    self._update_link_properties(link, link_dict, section='removed')
+                    self._update_link_properties(link, link_dict, section="removed")
 
     def update(self, data=None):
         """
@@ -340,7 +340,7 @@ def link_status_changed(self, link, status):
         # if using fetch strategy or
         # using receive strategy and link is coming back up or
         # receive strategy and ``expiration_time == 0``
-        elif self.strategy == 'fetch' or status == 'up' or self.expiration_time == 0:
+        elif self.strategy == "fetch" or status == "up" or self.expiration_time == 0:
             return True
         # if using receive strategy and expiration_time of link has expired
         elif link.modified < (now() - timedelta(seconds=self.expiration_time)):
@@ -361,9 +361,9 @@ def receive(self, data):
             Link = self.link_model
             netjson = data.json(dict=True)
             # update last modified date of all received links
-            for link_dict in netjson['links']:
+            for link_dict in netjson["links"]:
                 link = Link.get_from_nodes(
-                    link_dict['source'], link_dict['target'], topology=self
+                    link_dict["source"], link_dict["target"], topology=self
                 )
                 if link:
                     link.save()
@@ -376,12 +376,12 @@ def update_all(cls, label=None):
         - logs failures
         - calls delete_expired_links()
         """
-        queryset = cls.objects.filter(published=True, strategy='fetch')
+        queryset = cls.objects.filter(published=True, strategy="fetch")
         if label:
             queryset = queryset.filter(label__icontains=label)
         for topology in queryset:
-            print_info('Updating topology {0}'.format(topology))
-            with log_failure('update', topology):
+            print_info("Updating topology {0}".format(topology))
+            with log_failure("update", topology):
                 topology.update()
         cls().link_model.delete_expired_links()
         cls().node_model.delete_expired_nodes()
@@ -396,11 +396,11 @@ def save_snapshot_all(cls, label=None):
         if label:
             queryset = queryset.filter(label__icontains=label)
         for topology in queryset:
-            print_info('Saving topology {0}'.format(topology))
-            with log_failure('save_snapshot', topology):
+            print_info("Saving topology {0}".format(topology))
+            with log_failure("save_snapshot", topology):
                 topology.save_snapshot()
 
 
-@receiver(post_save, sender=swapper.get_model_name('topology', 'Topology'))
+@receiver(post_save, sender=swapper.get_model_name("topology", "Topology"))
 def send_topology_signal(sender, instance, **kwargs):
     update_topology.send(sender=sender, topology=instance)
diff --git a/openwisp_network_topology/consumers.py b/openwisp_network_topology/consumers.py
index 4f4fefb6..4e8563b4 100644
--- a/openwisp_network_topology/consumers.py
+++ b/openwisp_network_topology/consumers.py
@@ -7,11 +7,11 @@
 
 from . import settings as app_settings
 
-Topology = load_model('topology', 'Topology')
+Topology = load_model("topology", "Topology")
 
 
 class TopologyConsumer(WebsocketConsumer):
-    channel_layer_group = 'topology'
+    channel_layer_group = "topology"
 
     def _is_user_authorized_to_view_topology(self, user, topology_pk):
         try:
@@ -23,13 +23,13 @@ def _is_user_authorized_to_view_topology(self, user, topology_pk):
         return user.is_superuser or (
             user.is_authenticated
             and user.is_manager(topology.organization_id)
-            and user.has_perm(f'{Topology._meta.app_label}.view_topology')
+            and user.has_perm(f"{Topology._meta.app_label}.view_topology")
         )
 
     def connect(self):
-        user, topology_pk = self.scope.get('user'), self.scope.get('url_route').get(
-            'kwargs'
-        ).get('pk')
+        user, topology_pk = self.scope.get("user"), self.scope.get("url_route").get(
+            "kwargs"
+        ).get("pk")
         if self._is_user_authorized_to_view_topology(user, topology_pk):
             async_to_sync(self.channel_layer.group_add)(
                 f"{self.channel_layer_group}-{topology_pk}", self.channel_name
@@ -45,8 +45,8 @@ def send_topology_update(self, event):
         self.send(
             text_data=json.dumps(
                 {
-                    'type': "broadcast_topology",
-                    'topology': event['data'],
+                    "type": "broadcast_topology",
+                    "topology": event["data"],
                 }
             )
         )
diff --git a/openwisp_network_topology/contextmanagers.py b/openwisp_network_topology/contextmanagers.py
index e47c4622..96be865b 100644
--- a/openwisp_network_topology/contextmanagers.py
+++ b/openwisp_network_topology/contextmanagers.py
@@ -9,9 +9,9 @@ def log_failure(action, obj):
     try:
         yield
     except Exception as e:
-        msg = 'Failed to perform {0} on {1}'.format(action, obj.__repr__())
+        msg = "Failed to perform {0} on {1}".format(action, obj.__repr__())
         logger.exception(msg)
         print(
-            '{0}: {1}\nSee error log for more '
-            'information\n'.format(msg, e.__class__.__name__)
+            "{0}: {1}\nSee error log for more "
+            "information\n".format(msg, e.__class__.__name__)
         )
diff --git a/openwisp_network_topology/integrations/device/admin.py b/openwisp_network_topology/integrations/device/admin.py
index 9e76c8fc..c4c58761 100644
--- a/openwisp_network_topology/integrations/device/admin.py
+++ b/openwisp_network_topology/integrations/device/admin.py
@@ -5,8 +5,8 @@
 
 from . import settings as app_settings
 
-WifiMesh = load_model('topology_device', 'WifiMesh')
-Topology = load_model('topology', 'Topology')
+WifiMesh = load_model("topology_device", "WifiMesh")
+Topology = load_model("topology", "Topology")
 
 
 class WifiMeshInlineAdmin(admin.StackedInline):
diff --git a/openwisp_network_topology/integrations/device/apps.py b/openwisp_network_topology/integrations/device/apps.py
index 7f075289..8ad941c9 100644
--- a/openwisp_network_topology/integrations/device/apps.py
+++ b/openwisp_network_topology/integrations/device/apps.py
@@ -11,25 +11,25 @@
 
 
 class OpenwispTopologyDeviceConfig(AppConfig):
-    name = 'openwisp_network_topology.integrations.device'
-    label = 'topology_device'
-    verbose_name = _('Topology Device Integration')
+    name = "openwisp_network_topology.integrations.device"
+    label = "topology_device"
+    verbose_name = _("Topology Device Integration")
 
     def ready(self):
         self.connect_signals()
         self.override_node_label()
 
     def connect_signals(self):
-        Node = swapper.load_model('topology', 'Node')
-        Link = swapper.load_model('topology', 'Link')
+        Node = swapper.load_model("topology", "Node")
+        Link = swapper.load_model("topology", "Link")
 
         post_save.connect(
-            self.create_device_rel, sender=Node, dispatch_uid='node_to_device_rel'
+            self.create_device_rel, sender=Node, dispatch_uid="node_to_device_rel"
         )
         link_status_changed.connect(
             self.link_status_changed_receiver,
             sender=Link,
-            dispatch_uid='controller_integration_link_status_chaged',
+            dispatch_uid="controller_integration_link_status_chaged",
         )
 
     @classmethod
@@ -43,4 +43,4 @@ def link_status_changed_receiver(cls, link, **kwargs):
         transaction.on_commit(lambda: trigger_device_updates.delay(link.pk))
 
     def override_node_label(self):
-        import_module('openwisp_network_topology.integrations.device.overrides')
+        import_module("openwisp_network_topology.integrations.device.overrides")
diff --git a/openwisp_network_topology/integrations/device/base/models.py b/openwisp_network_topology/integrations/device/base/models.py
index 8307171b..cbf38c1d 100644
--- a/openwisp_network_topology/integrations/device/base/models.py
+++ b/openwisp_network_topology/integrations/device/base/models.py
@@ -15,38 +15,38 @@
 
 logger = logging.getLogger(__name__)
 
-trigger_device_checks_path = 'openwisp_monitoring.device.tasks.trigger_device_checks'
+trigger_device_checks_path = "openwisp_monitoring.device.tasks.trigger_device_checks"
 
 
 class AbstractDeviceNode(UUIDModel):
     node = models.OneToOneField(
-        get_model_name('topology', 'Node'), on_delete=models.CASCADE
+        get_model_name("topology", "Node"), on_delete=models.CASCADE
     )
     device = models.ForeignKey(
-        get_model_name('config', 'Device'), on_delete=models.CASCADE
+        get_model_name("config", "Device"), on_delete=models.CASCADE
     )
 
     # relations will be auto-created only for these parsers
     ENABLED_PARSERS = {
-        'netdiff.OpenvpnParser': {
-            'auto_create': 'auto_create_openvpn',
-            'link_down': 'link_down_openvpn',
-            'link_up': 'link_up_openvpn',
+        "netdiff.OpenvpnParser": {
+            "auto_create": "auto_create_openvpn",
+            "link_down": "link_down_openvpn",
+            "link_up": "link_up_openvpn",
         },
-        'netdiff.WireguardParser': {
-            'auto_create': 'auto_create_wireguard',
+        "netdiff.WireguardParser": {
+            "auto_create": "auto_create_wireguard",
         },
-        'netdiff.ZeroTierParser': {
-            'auto_create': 'auto_create_zerotier',
+        "netdiff.ZeroTierParser": {
+            "auto_create": "auto_create_zerotier",
         },
-        'netdiff.NetJsonParser': {
-            'auto_create': 'auto_create_netjsongraph',
+        "netdiff.NetJsonParser": {
+            "auto_create": "auto_create_netjsongraph",
         },
     }
 
     class Meta:
         abstract = True
-        unique_together = ('node', 'device')
+        unique_together = ("node", "device")
 
     @classmethod
     def save_device_node(cls, device, node):
@@ -58,12 +58,12 @@ def save_device_node(cls, device, node):
             # when topology is shared.
             if node.organization_id is None:
                 node.organization_id = device.organization_id
-                node.save(update_fields=['organization_id'])
+                node.save(update_fields=["organization_id"])
         except Exception:
-            logger.exception('Exception raised during save_device_node')
+            logger.exception("Exception raised during save_device_node")
             return
         else:
-            logger.info(f'DeviceNode relation created for {node.label} - {device.name}')
+            logger.info(f"DeviceNode relation created for {node.label} - {device.name}")
             return device_node
 
     @classmethod
@@ -74,7 +74,7 @@ def auto_create(cls, node):
         """
         opts = cls.ENABLED_PARSERS.get(node.topology.parser)
         if opts:
-            return getattr(cls, opts['auto_create'])(node)
+            return getattr(cls, opts["auto_create"])(node)
 
     @classmethod
     def auto_create_openvpn(cls, node):
@@ -83,17 +83,17 @@ def auto_create_openvpn(cls, node):
         controller and network-topology modules
         when using OpenVPN (using the common name)
         """
-        common_name = node.properties.get('common_name')
+        common_name = node.properties.get("common_name")
         if not common_name:
             return
 
-        Device = load_model('config', 'Device')
+        Device = load_model("config", "Device")
         device_filter = models.Q(config__vpnclient__cert__common_name=common_name)
         if node.organization_id:
             device_filter &= models.Q(organization_id=node.organization_id)
         device = (
             Device.objects.only(
-                'id', 'name', 'last_ip', 'management_ip', 'organization_id'
+                "id", "name", "last_ip", "management_ip", "organization_id"
             )
             .filter(device_filter)
             .first()
@@ -105,10 +105,10 @@ def auto_create_openvpn(cls, node):
 
     @classmethod
     def auto_create_wireguard(cls, node):
-        allowed_ips = node.properties.get('allowed_ips')
+        allowed_ips = node.properties.get("allowed_ips")
         if not allowed_ips:
             return
-        Device = load_model('config', 'Device')
+        Device = load_model("config", "Device")
         ip_addresses = []
         for ip in allowed_ips:
             try:
@@ -121,7 +121,7 @@ def auto_create_wireguard(cls, node):
             device_filter &= models.Q(organization_id=node.organization_id)
         device = (
             Device.objects.only(
-                'id', 'name', 'last_ip', 'management_ip', 'organization_id'
+                "id", "name", "last_ip", "management_ip", "organization_id"
             )
             .filter(device_filter)
             .first()
@@ -137,11 +137,11 @@ def auto_create_zerotier(cls, node):
         controller and network-topology modules
         when using ZeroTier (using the `zerotier_member_id`)
         """
-        zerotier_member_id = node.properties.get('address')
+        zerotier_member_id = node.properties.get("address")
         if not zerotier_member_id:
             return
 
-        Device = load_model('config', 'Device')
+        Device = load_model("config", "Device")
         device_filter = models.Q(
             config__vpnclient__secret__startswith=zerotier_member_id
         )
@@ -149,7 +149,7 @@ def auto_create_zerotier(cls, node):
             device_filter &= models.Q(organization_id=node.organization_id)
         device = (
             Device.objects.only(
-                'id', 'name', 'last_ip', 'management_ip', 'organization_id'
+                "id", "name", "last_ip", "management_ip", "organization_id"
             )
             .filter(device_filter)
             .first()
@@ -166,15 +166,15 @@ def auto_create_netjsongraph(cls, node):
             # If a node only has one MAC address, it means that
             # it only contains interface MAC address.
             return
-        Device = load_model('config', 'Device')
+        Device = load_model("config", "Device")
         device_filter = models.Q(
-            mac_address__iexact=node.addresses[0].rpartition('@')[0]
+            mac_address__iexact=node.addresses[0].rpartition("@")[0]
         )
         if node.organization_id:
             device_filter &= models.Q(organization_id=node.organization_id)
         device = (
             Device.objects.only(
-                'id', 'name', 'last_ip', 'management_ip', 'organization_id'
+                "id", "name", "last_ip", "management_ip", "organization_id"
             )
             .filter(device_filter)
             .first()
@@ -190,7 +190,7 @@ def link_action(self, link, status):
         """
         opts = self.ENABLED_PARSERS.get(link.topology.parser)
         if opts:
-            key = f'link_{status}'
+            key = f"link_{status}"
             if key in opts and hasattr(self, opts[key]):
                 return getattr(self, opts[key])()
 
@@ -209,9 +209,9 @@ def link_up_openvpn(self):
         try:
             address = ip_address(addresses[1])
         except (IndexError, ValueError) as e:
-            addresses = ', '.join(addresses)
+            addresses = ", ".join(addresses)
             logger.warning(
-                f'{e.__class__.__name__} raised while processing addresses: {addresses}'
+                f"{e.__class__.__name__} raised while processing addresses: {addresses}"
             )
         else:
             self.device.management_ip = str(address)
@@ -226,7 +226,7 @@ def filter_by_link(cls, link):
         return cls.objects.filter(
             models.Q(node__source_link_set__pk=link.pk)
             | models.Q(node__target_link_set__pk=link.pk)
-        ).select_related('device', 'node')
+        ).select_related("device", "node")
 
     @classmethod
     def trigger_device_updates(cls, link):
@@ -239,37 +239,37 @@ def trigger_device_updates(cls, link):
         for device_node in cls.filter_by_link(link):
             device_node.link_action(link, link.status)
             # triggers monitoring checks if OpenWISP Monitoring is enabled
-            if 'openwisp_monitoring.device' in settings.INSTALLED_APPS:
+            if "openwisp_monitoring.device" in settings.INSTALLED_APPS:
                 run_checks = import_string(trigger_device_checks_path)
-                run_checks.delay(device_node.device.pk, recovery=link.status == 'up')
+                run_checks.delay(device_node.device.pk, recovery=link.status == "up")
 
 
 class AbstractWifiMesh(UUIDModel):
     _NODE_PROPERTIES = [
-        'ht',
-        'vht',
-        'he',
-        'mfp',
-        'wmm',
-        'vendor',
+        "ht",
+        "vht",
+        "he",
+        "mfp",
+        "wmm",
+        "vendor",
     ]
     _LINK_PROPERTIES = [
-        'auth',
-        'authorized',
-        'noise',
-        'signal',
-        'signal_avg',
-        'mesh_llid',
-        'mesh_plid',
-        'mesh_plink',
-        'mesh_non_peer_ps',
+        "auth",
+        "authorized",
+        "noise",
+        "signal",
+        "signal_avg",
+        "mesh_llid",
+        "mesh_plid",
+        "mesh_plink",
+        "mesh_non_peer_ps",
     ]
 
     topology = models.ForeignKey(
-        get_model_name('topology', 'Topology'), on_delete=models.CASCADE
+        get_model_name("topology", "Topology"), on_delete=models.CASCADE
     )
     mesh_id = models.CharField(
-        max_length=32, null=False, blank=False, verbose_name=_('Mesh ID')
+        max_length=32, null=False, blank=False, verbose_name=_("Mesh ID")
     )
 
     class Meta:
@@ -281,7 +281,7 @@ def create_topology(cls, organization_ids, discard_older_data_time):
             raise ImproperlyConfigured(
                 '"OPENIWSP_NETWORK_TOPOLOGY_WIFI_MESH_INTEGRATION" is set to "False".'
             )
-        Link = load_model('topology', 'Link')
+        Link = load_model("topology", "Link")
         for org_id in organization_ids:
             intermediate_topologies = cls._create_intermediate_topologies(
                 org_id, discard_older_data_time
@@ -290,7 +290,7 @@ def create_topology(cls, organization_ids, discard_older_data_time):
                 Link.objects.filter(
                     topology__wifimesh__isnull=False, organization_id=org_id
                 ).exclude(topology__wifimesh__in=intermediate_topologies.keys()).update(
-                    status='down'
+                    status="down"
                 )
                 continue
             cls._create_topology(intermediate_topologies, org_id)
@@ -309,10 +309,10 @@ def _create_intermediate_topologies(cls, organization_id, discard_older_data_tim
         These individual topologies are then complied to create the
         complete mesh topology.
         """
-        DeviceData = load_model('device_monitoring', 'DeviceData')
+        DeviceData = load_model("device_monitoring", "DeviceData")
         intermediate_topologies = {}
         query = DeviceData.objects.filter(organization_id=organization_id).only(
-            'mac_address'
+            "mac_address"
         )
         discard_older_data_time = now() - timedelta(seconds=discard_older_data_time)
         for device_data in query.iterator():
@@ -322,30 +322,30 @@ def _create_intermediate_topologies(cls, organization_id, discard_older_data_tim
                 assert data_timestamp > discard_older_data_time
             except (AttributeError, AssertionError):
                 continue
-            for interface in device_data.data.get('interfaces', []):
+            for interface in device_data.data.get("interfaces", []):
                 if not AbstractWifiMesh._is_mesh_interfaces(interface):
                     continue
-                mesh_id = '{}@{}'.format(
-                    interface['wireless']['ssid'], interface['wireless']['channel']
+                mesh_id = "{}@{}".format(
+                    interface["wireless"]["ssid"], interface["wireless"]["channel"]
                 )
                 if mesh_id not in intermediate_topologies:
                     intermediate_topologies[mesh_id] = {
-                        'nodes': {},
-                        'links': {},
-                        'mac_mapping': {},
+                        "nodes": {},
+                        "links": {},
+                        "mac_mapping": {},
                     }
                 topology = intermediate_topologies[mesh_id]
                 (
                     collected_nodes,
                     collected_links,
                 ) = cls._get_intermediate_nodes_and_links(
-                    interface, device_data, topology['mac_mapping']
+                    interface, device_data, topology["mac_mapping"]
                 )
                 AbstractWifiMesh._merge_nodes(
-                    interface, topology['nodes'], collected_nodes
+                    interface, topology["nodes"], collected_nodes
                 )
                 AbstractWifiMesh._merge_links(
-                    interface, topology['links'], collected_links
+                    interface, topology["links"], collected_links
                 )
         return intermediate_topologies
 
@@ -360,20 +360,20 @@ def _get_intermediate_nodes_and_links(cls, interface, device_data, mac_mapping):
         device MAC address.
         """
         device_mac = device_data.mac_address.upper()
-        interface_mac = interface['mac'].upper()
-        channel = interface['wireless']['channel']
-        device_node_id = f'{device_mac}@{channel}'
+        interface_mac = interface["mac"].upper()
+        channel = interface["wireless"]["channel"]
+        device_node_id = f"{device_mac}@{channel}"
         mac_mapping[interface_mac] = device_node_id
         collected_nodes = {}
         collected_links = {}
-        for client in interface['wireless'].get('clients', []):
-            client_mac = client['mac'].upper()
+        for client in interface["wireless"].get("clients", []):
+            client_mac = client["mac"].upper()
             node_properties = {}
             for property in cls._NODE_PROPERTIES:
                 if property in client:
                     node_properties[property] = client[property]
-            collected_nodes[client_mac] = {'properties': node_properties}
-            if client.get('mesh_plink') and client.get('mesh_plink') != 'ESTAB':
+            collected_nodes[client_mac] = {"properties": node_properties}
+            if client.get("mesh_plink") and client.get("mesh_plink") != "ESTAB":
                 # The link is not established.
                 # Do not add this link to the topology.
                 continue
@@ -384,23 +384,23 @@ def _get_intermediate_nodes_and_links(cls, interface, device_data, mac_mapping):
 
             collected_links[client_mac] = {
                 interface_mac: {
-                    'source': f'{device_mac}@{channel}',
-                    'target': f'{client_mac}',
-                    'cost': 1.0,
-                    'properties': link_properties,
+                    "source": f"{device_mac}@{channel}",
+                    "target": f"{client_mac}",
+                    "cost": 1.0,
+                    "properties": link_properties,
                 }
             }
         return collected_nodes, collected_links
 
     @staticmethod
     def _is_mesh_interfaces(interface):
-        return interface.get('wireless', False) and interface['wireless'].get(
-            'mode'
-        ) in ['802.11s']
+        return interface.get("wireless", False) and interface["wireless"].get(
+            "mode"
+        ) in ["802.11s"]
 
     @staticmethod
     def _merge_nodes(interface, topology_nodes, collected_nodes):
-        interface_mac = interface['mac'].upper()
+        interface_mac = interface["mac"].upper()
         topology_nodes.update(collected_nodes)
         if not topology_nodes.get(interface_mac):
             # Handle case when there is only one node present
@@ -417,39 +417,39 @@ def _merge_links(interface, topology_links, collected_links):
         It takes into consideration the nature of the property
         (e.g. taking average for signal and noise, etc.).
         """
-        interface_mac = interface['mac'].upper()
+        interface_mac = interface["mac"].upper()
         if topology_links.get(interface_mac):
             for source, topology_link in topology_links[interface_mac].items():
                 if not collected_links.get(source):
                     continue
                 for property, value in collected_links[source][interface_mac][
-                    'properties'
+                    "properties"
                 ].items():
                     if isinstance(value, int):
                         # If the value is integer, then take average of the
                         # values provided by the two nodes.
                         # This is for fields like signal and noise.
-                        if topology_link['properties'].get(property):
-                            topology_link['properties'][property] = (
-                                value + topology_link['properties'][property]
+                        if topology_link["properties"].get(property):
+                            topology_link["properties"][property] = (
+                                value + topology_link["properties"][property]
                             ) // 2
                         else:
                             # The link in topology does not contain this property,
                             # hence instead of averaging, assign the current value.
-                            topology_link['properties'][property] = value
+                            topology_link["properties"][property] = value
                     elif (
-                        property in ['mesh_plink', 'mesh_non_peer_ps']
-                        and topology_link['properties'].get(property)
-                        and value != topology_link['properties'][property]
+                        property in ["mesh_plink", "mesh_non_peer_ps"]
+                        and topology_link["properties"].get(property)
+                        and value != topology_link["properties"][property]
                     ):
                         # The value for "mesh_plink" and "mesh_non_peer_ps" properties
                         # should be reported same by both the nodes.
                         # Flag the value as inconsistent if they are different.
-                        topology_link['properties'][
-                            property
-                        ] = 'INCONSISTENT: ({} / {})'.format(
-                            value,
-                            topology_link['properties'][property],
+                        topology_link["properties"][property] = (
+                            "INCONSISTENT: ({} / {})".format(
+                                value,
+                                topology_link["properties"][property],
+                            )
                         )
                 collected_links.pop(source)
         for key, value in collected_links.items():
@@ -465,12 +465,12 @@ def _create_topology(intermediate_topologies, organization_id):
             nodes = AbstractWifiMesh._get_nodes_from_intermediate_topology(intermediate)
             links = AbstractWifiMesh._get_links_from_intermediate_topology(intermediate)
             topology = {
-                'type': 'NetworkGraph',
-                'protocol': 'Mesh',
-                'version': '1',
-                'metric': 'Airtime',
-                'nodes': nodes,
-                'links': links,
+                "type": "NetworkGraph",
+                "protocol": "Mesh",
+                "version": "1",
+                "metric": "Airtime",
+                "nodes": nodes,
+                "links": links,
             }
             topology_obj.receive(topology)
 
@@ -484,18 +484,18 @@ def _get_nodes_from_intermediate_topology(intermediate_topology):
         which is used to create DeviceNode relation.
         """
         nodes = []
-        mac_mapping = intermediate_topology['mac_mapping']
-        for interface_mac, intermediate_node in intermediate_topology['nodes'].items():
+        mac_mapping = intermediate_topology["mac_mapping"]
+        for interface_mac, intermediate_node in intermediate_topology["nodes"].items():
             device_mac = mac_mapping.get(interface_mac)
             if not device_mac:
                 continue
             node = {
-                'id': device_mac,
-                'label': device_mac,
-                'local_addresses': [interface_mac],
+                "id": device_mac,
+                "label": device_mac,
+                "local_addresses": [interface_mac],
             }
-            if intermediate_node.get('properties'):
-                node['properties'] = intermediate_node['properties']
+            if intermediate_node.get("properties"):
+                node["properties"] = intermediate_node["properties"]
             nodes.append(node)
         return nodes
 
@@ -508,13 +508,13 @@ def _get_links_from_intermediate_topology(intermediate_topology):
         It maps the interface's MAC address to the device's main MAC address.
         """
         links = []
-        mac_mapping = intermediate_topology['mac_mapping']
-        for interface_mac, intermediate_link in intermediate_topology['links'].items():
+        mac_mapping = intermediate_topology["mac_mapping"]
+        for interface_mac, intermediate_link in intermediate_topology["links"].items():
             device_mac = mac_mapping.get(interface_mac)
             if not device_mac:
                 continue
             for link in intermediate_link.values():
-                link['target'] = device_mac
+                link["target"] = device_mac
                 links.append(link)
         return links
 
@@ -525,11 +525,11 @@ def _get_mesh_topology(mesh_id, organization_id):
         It also creates WifiMesh object to keep track of mesh's ID
         if a new topology object is created.
         """
-        Topology = load_model('topology', 'Topology')
-        WifiMesh = load_model('topology_device', 'WifiMesh')
+        Topology = load_model("topology", "Topology")
+        WifiMesh = load_model("topology_device", "WifiMesh")
         try:
             mesh_topology = (
-                WifiMesh.objects.select_related('topology')
+                WifiMesh.objects.select_related("topology")
                 .get(
                     mesh_id=mesh_id,
                     topology__organization_id=organization_id,
@@ -540,8 +540,8 @@ def _get_mesh_topology(mesh_id, organization_id):
             mesh_topology = Topology(
                 organization_id=organization_id,
                 label=mesh_id,
-                parser='netdiff.NetJsonParser',
-                strategy='receive',
+                parser="netdiff.NetJsonParser",
+                strategy="receive",
                 expiration_time=330,
             )
             mesh_topology.full_clean()
diff --git a/openwisp_network_topology/integrations/device/management/commands/__init__.py b/openwisp_network_topology/integrations/device/management/commands/__init__.py
index 36590ef4..4e2bd747 100644
--- a/openwisp_network_topology/integrations/device/management/commands/__init__.py
+++ b/openwisp_network_topology/integrations/device/management/commands/__init__.py
@@ -4,15 +4,15 @@
 
 
 class BaseCreateDeviceNodeCommand(BaseCommand):
-    help = 'Create initial DeviceNode objects'
+    help = "Create initial DeviceNode objects"
 
     def handle(self, *args, **kwargs):
-        Node = swapper.load_model('topology', 'Node')
-        DeviceNode = swapper.load_model('topology_device', 'DeviceNode')
-        queryset = Node.objects.select_related('topology').filter(
-            Q(topology__parser='netdiff.OpenvpnParser')
-            | Q(topology__parser='netdiff.WireguardParser')
-            | Q(topology__parser='netdiff.ZeroTierParser')
+        Node = swapper.load_model("topology", "Node")
+        DeviceNode = swapper.load_model("topology_device", "DeviceNode")
+        queryset = Node.objects.select_related("topology").filter(
+            Q(topology__parser="netdiff.OpenvpnParser")
+            | Q(topology__parser="netdiff.WireguardParser")
+            | Q(topology__parser="netdiff.ZeroTierParser")
         )
         for node in queryset.iterator():
             DeviceNode.auto_create(node)
diff --git a/openwisp_network_topology/integrations/device/migrations/0001_initial.py b/openwisp_network_topology/integrations/device/migrations/0001_initial.py
index e4954792..bd70de8d 100644
--- a/openwisp_network_topology/integrations/device/migrations/0001_initial.py
+++ b/openwisp_network_topology/integrations/device/migrations/0001_initial.py
@@ -11,16 +11,16 @@ class Migration(migrations.Migration):
     initial = True
 
     dependencies = [
-        swapper.dependency('topology', 'Node'),
-        swapper.dependency('config', 'Device'),
+        swapper.dependency("topology", "Node"),
+        swapper.dependency("config", "Device"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='DeviceNode',
+            name="DeviceNode",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -29,24 +29,24 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'device',
+                    "device",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=swapper.get_model_name('config', 'Device'),
+                        to=swapper.get_model_name("config", "Device"),
                     ),
                 ),
                 (
-                    'node',
+                    "node",
                     models.OneToOneField(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=swapper.get_model_name('topology', 'Node'),
+                        to=swapper.get_model_name("topology", "Node"),
                     ),
                 ),
             ],
             options={
-                'abstract': False,
-                'swappable': swapper.swappable_setting('topology_device', 'DeviceNode'),
-                'unique_together': {('node', 'device')},
+                "abstract": False,
+                "swappable": swapper.swappable_setting("topology_device", "DeviceNode"),
+                "unique_together": {("node", "device")},
             },
         )
     ]
diff --git a/openwisp_network_topology/integrations/device/migrations/0002_wifimesh.py b/openwisp_network_topology/integrations/device/migrations/0002_wifimesh.py
index beae89d5..419e0c0c 100644
--- a/openwisp_network_topology/integrations/device/migrations/0002_wifimesh.py
+++ b/openwisp_network_topology/integrations/device/migrations/0002_wifimesh.py
@@ -10,15 +10,15 @@
 class Migration(migrations.Migration):
     dependencies = [
         migrations.swappable_dependency(settings.TOPOLOGY_TOPOLOGY_MODEL),
-        ('topology_device', '0001_initial'),
+        ("topology_device", "0001_initial"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='WifiMesh',
+            name="WifiMesh",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -26,9 +26,9 @@ class Migration(migrations.Migration):
                         serialize=False,
                     ),
                 ),
-                ('mesh_id', models.CharField(max_length=32, verbose_name='Mesh ID')),
+                ("mesh_id", models.CharField(max_length=32, verbose_name="Mesh ID")),
                 (
-                    'topology',
+                    "topology",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
                         to=settings.TOPOLOGY_TOPOLOGY_MODEL,
@@ -36,8 +36,8 @@ class Migration(migrations.Migration):
                 ),
             ],
             options={
-                'abstract': False,
-                'swappable': 'TOPOLOGY_DEVICE_WIFIMESH_MODEL',
+                "abstract": False,
+                "swappable": "TOPOLOGY_DEVICE_WIFIMESH_MODEL",
             },
         ),
     ]
diff --git a/openwisp_network_topology/integrations/device/migrations/0003_wifimesh_permissions.py b/openwisp_network_topology/integrations/device/migrations/0003_wifimesh_permissions.py
index bd8a0e80..f2420aa0 100644
--- a/openwisp_network_topology/integrations/device/migrations/0003_wifimesh_permissions.py
+++ b/openwisp_network_topology/integrations/device/migrations/0003_wifimesh_permissions.py
@@ -13,31 +13,31 @@ def _add_permission_to_group(group, models, operations):
             for operation in operations:
                 try:
                     permission = Permission.objects.get(
-                        codename='{}_{}'.format(operation, model)
+                        codename="{}_{}".format(operation, model)
                     )
                 except Permission.DoesNotExist:
                     continue
                 else:
                     group.permissions.add(permission.pk)
 
-    Group = apps.get_model('openwisp_users', 'Group')
-    manage_operations = ['add', 'change', 'delete', 'view']
+    Group = apps.get_model("openwisp_users", "Group")
+    manage_operations = ["add", "change", "delete", "view"]
     try:
-        admin = Group.objects.get(name='Administrator')
-        operator = Group.objects.get(name='Operator')
+        admin = Group.objects.get(name="Administrator")
+        operator = Group.objects.get(name="Operator")
     # consider failures custom cases
     # that do not have to be dealt with
     except Group.DoesNotExist:
         return
 
-    _add_permission_to_group(operator, ['wifimesh'], manage_operations)
-    _add_permission_to_group(admin, ['wifimesh'], manage_operations)
+    _add_permission_to_group(operator, ["wifimesh"], manage_operations)
+    _add_permission_to_group(admin, ["wifimesh"], manage_operations)
 
 
 class Migration(migrations.Migration):
     dependencies = [
         migrations.swappable_dependency(settings.TOPOLOGY_TOPOLOGY_MODEL),
-        ('topology_device', '0002_wifimesh'),
+        ("topology_device", "0002_wifimesh"),
     ]
 
     operations = [
diff --git a/openwisp_network_topology/integrations/device/models.py b/openwisp_network_topology/integrations/device/models.py
index f3835b02..3c5c470c 100644
--- a/openwisp_network_topology/integrations/device/models.py
+++ b/openwisp_network_topology/integrations/device/models.py
@@ -6,10 +6,10 @@
 class DeviceNode(AbstractDeviceNode):
     class Meta(AbstractDeviceNode.Meta):
         abstract = False
-        swappable = swappable_setting('topology_device', 'DeviceNode')
+        swappable = swappable_setting("topology_device", "DeviceNode")
 
 
 class WifiMesh(AbstractWifiMesh):
     class Meta(AbstractWifiMesh.Meta):
         abstract = False
-        swappable = swappable_setting('topology_device', 'WifiMesh')
+        swappable = swappable_setting("topology_device", "WifiMesh")
diff --git a/openwisp_network_topology/integrations/device/overrides.py b/openwisp_network_topology/integrations/device/overrides.py
index 60ab167b..c334eea5 100644
--- a/openwisp_network_topology/integrations/device/overrides.py
+++ b/openwisp_network_topology/integrations/device/overrides.py
@@ -1,19 +1,19 @@
 import swapper
 from django.utils.translation import gettext_lazy as _
 
-Node = swapper.load_model('topology', 'Node')
-Link = swapper.load_model('topology', 'Link')
-Topology = swapper.load_model('topology', 'Topology')
+Node = swapper.load_model("topology", "Node")
+Link = swapper.load_model("topology", "Link")
+Topology = swapper.load_model("topology", "Topology")
 
 
 def get_name(self):
-    if hasattr(self, 'devicenode'):
+    if hasattr(self, "devicenode"):
         return self.devicenode.device.name
     return super(Node, self).get_name()
 
 
 def node_get_organization_id(self):
-    if hasattr(self, 'devicenode'):
+    if hasattr(self, "devicenode"):
         return self.devicenode.device.organization_id
     return super(Node, self).get_organization_id()
 
@@ -27,20 +27,20 @@ def topology_get_nodes_queryset(self):
     return (
         super(Topology, self)
         .get_nodes_queryset()
-        .select_related('devicenode__device')
+        .select_related("devicenode__device")
         .only(
-            'id',
-            'topology_id',
-            'label',
-            'addresses',
-            'properties',
-            'user_properties',
-            'created',
-            'modified',
-            'devicenode__device__id',
-            'devicenode__device__name',
-            'devicenode__device__last_ip',
-            'devicenode__device__management_ip',
+            "id",
+            "topology_id",
+            "label",
+            "addresses",
+            "properties",
+            "user_properties",
+            "created",
+            "modified",
+            "devicenode__device__id",
+            "devicenode__device__name",
+            "devicenode__device__last_ip",
+            "devicenode__device__management_ip",
         )
     )
 
@@ -50,24 +50,24 @@ def node_get_queryset(cls, qs):
     return (
         super(Node, cls)
         .get_queryset(qs)
-        .select_related('devicenode__device')
+        .select_related("devicenode__device")
         .only(
-            'id',
-            'topology_id',
-            'topology__label',
-            'topology__parser',
-            'organization__id',
-            'organization__name',
-            'organization__is_active',
-            'label',
-            'addresses',
-            'properties',
-            'user_properties',
-            'devicenode__device__id',
-            'devicenode__device__name',
-            'devicenode__device__name',
-            'devicenode__device__last_ip',
-            'devicenode__device__management_ip',
+            "id",
+            "topology_id",
+            "topology__label",
+            "topology__parser",
+            "organization__id",
+            "organization__name",
+            "organization__is_active",
+            "label",
+            "addresses",
+            "properties",
+            "user_properties",
+            "devicenode__device__id",
+            "devicenode__device__name",
+            "devicenode__device__name",
+            "devicenode__device__last_ip",
+            "devicenode__device__management_ip",
         )
     )
 
@@ -77,38 +77,38 @@ def link_get_queryset(cls, qs):
     return (
         super(Link, cls)
         .get_queryset(qs)
-        .select_related('source__devicenode__device', 'target__devicenode__device')
+        .select_related("source__devicenode__device", "target__devicenode__device")
         .only(
-            'id',
-            'topology_id',
-            'topology__label',
-            'topology__parser',
-            'organization__id',
-            'organization__name',
-            'organization__is_active',
-            'status',
-            'properties',
-            'user_properties',
-            'cost',
-            'cost_text',
-            'source__addresses',
-            'source__label',
-            'source__devicenode__device__id',
-            'source__devicenode__device__name',
-            'source__devicenode__device__last_ip',
-            'source__devicenode__device__management_ip',
-            'target__addresses',
-            'target__label',
-            'target__devicenode__device__id',
-            'target__devicenode__device__name',
-            'target__devicenode__device__last_ip',
-            'target__devicenode__device__management_ip',
+            "id",
+            "topology_id",
+            "topology__label",
+            "topology__parser",
+            "organization__id",
+            "organization__name",
+            "organization__is_active",
+            "status",
+            "properties",
+            "user_properties",
+            "cost",
+            "cost_text",
+            "source__addresses",
+            "source__label",
+            "source__devicenode__device__id",
+            "source__devicenode__device__name",
+            "source__devicenode__device__last_ip",
+            "source__devicenode__device__management_ip",
+            "target__addresses",
+            "target__label",
+            "target__devicenode__device__id",
+            "target__devicenode__device__name",
+            "target__devicenode__device__last_ip",
+            "target__devicenode__device__management_ip",
         )
     )
 
 
 Node.get_name = get_name
-Node.get_name.short_description = _('label')
+Node.get_name.short_description = _("label")
 Node.get_organization_id = node_get_organization_id
 Node.get_queryset = node_get_queryset
 Link.get_queryset = link_get_queryset
diff --git a/openwisp_network_topology/integrations/device/settings.py b/openwisp_network_topology/integrations/device/settings.py
index abb7bf32..d8ba6bfa 100644
--- a/openwisp_network_topology/integrations/device/settings.py
+++ b/openwisp_network_topology/integrations/device/settings.py
@@ -1,3 +1,3 @@
 from ...settings import get_settings_value
 
-WIFI_MESH_INTEGRATION = get_settings_value('WIFI_MESH_INTEGRATION', False)
+WIFI_MESH_INTEGRATION = get_settings_value("WIFI_MESH_INTEGRATION", False)
diff --git a/openwisp_network_topology/integrations/device/tasks.py b/openwisp_network_topology/integrations/device/tasks.py
index 629d2f6e..8d2b36ce 100644
--- a/openwisp_network_topology/integrations/device/tasks.py
+++ b/openwisp_network_topology/integrations/device/tasks.py
@@ -6,17 +6,17 @@
 
 @shared_task
 def create_device_node_relation(node_pk):
-    Node = swapper.load_model('topology', 'Node')
-    DeviceNode = swapper.load_model('topology_device', 'DeviceNode')
-    node = Node.objects.select_related('topology').get(pk=node_pk)
+    Node = swapper.load_model("topology", "Node")
+    DeviceNode = swapper.load_model("topology_device", "DeviceNode")
+    node = Node.objects.select_related("topology").get(pk=node_pk)
     DeviceNode.auto_create(node)
 
 
 @shared_task
 def trigger_device_updates(link_pk):
-    Link = swapper.load_model('topology', 'Link')
-    DeviceNode = swapper.load_model('topology_device', 'DeviceNode')
-    link = Link.objects.select_related('topology').get(pk=link_pk)
+    Link = swapper.load_model("topology", "Link")
+    DeviceNode = swapper.load_model("topology_device", "DeviceNode")
+    link = Link.objects.select_related("topology").get(pk=link_pk)
     DeviceNode.trigger_device_updates(link)
 
 
@@ -24,5 +24,5 @@ def trigger_device_updates(link_pk):
 def create_mesh_topology(organization_ids, discard_older_data_time=360):
     if not app_settings.WIFI_MESH_INTEGRATION:
         return
-    WifiMesh = swapper.load_model('topology_device', 'WifiMesh')
+    WifiMesh = swapper.load_model("topology_device", "WifiMesh")
     WifiMesh.create_topology(organization_ids, discard_older_data_time)
diff --git a/openwisp_network_topology/integrations/device/tests/__init__.py b/openwisp_network_topology/integrations/device/tests/__init__.py
index 672645c1..153d5469 100644
--- a/openwisp_network_topology/integrations/device/tests/__init__.py
+++ b/openwisp_network_topology/integrations/device/tests/__init__.py
@@ -1,220 +1,220 @@
 SIMPLE_MESH_DATA = {
-    '64:70:02:C3:03:B2': [
+    "64:70:02:C3:03:B2": [
         {
-            'mac': '64:70:02:c3:03:b3',
-            'mtu': 1500,
-            'multicast': True,
-            'name': 'mesh0',
-            'txqueuelen': 1000,
-            'type': 'wireless',
-            'up': True,
-            'wireless': {
-                'channel': 11,
-                'clients': [
+            "mac": "64:70:02:c3:03:b3",
+            "mtu": 1500,
+            "multicast": True,
+            "name": "mesh0",
+            "txqueuelen": 1000,
+            "type": "wireless",
+            "up": True,
+            "wireless": {
+                "channel": 11,
+                "clients": [
                     {
-                        'auth': True,
-                        'authorized': True,
-                        'ht': True,
-                        'mac': 'a4:bc:3f:ae:c7:0c',
-                        'mfp': False,
-                        'noise': -90,
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'vht': False,
-                        'wmm': True,
-                        'mesh_llid': 19000,
-                        'mesh_plid': 24000,
-                        'mesh_non_peer_ps': 'ACTIVE',
+                        "auth": True,
+                        "authorized": True,
+                        "ht": True,
+                        "mac": "a4:bc:3f:ae:c7:0c",
+                        "mfp": False,
+                        "noise": -90,
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "vht": False,
+                        "wmm": True,
+                        "mesh_llid": 19000,
+                        "mesh_plid": 24000,
+                        "mesh_non_peer_ps": "ACTIVE",
                     },
                     {
-                        'auth': True,
-                        'authorized': True,
-                        'ht': True,
-                        'mac': '2a:9a:fb:12:11:77',
-                        'mfp': False,
-                        'noise': -94,
-                        'signal': -58,
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'vht': False,
-                        'wmm': True,
-                        'mesh_llid': 19500,
-                        'mesh_plid': 24500,
-                        'mesh_non_peer_ps': 'ACTIVE',
+                        "auth": True,
+                        "authorized": True,
+                        "ht": True,
+                        "mac": "2a:9a:fb:12:11:77",
+                        "mfp": False,
+                        "noise": -94,
+                        "signal": -58,
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "vht": False,
+                        "wmm": True,
+                        "mesh_llid": 19500,
+                        "mesh_plid": 24500,
+                        "mesh_non_peer_ps": "ACTIVE",
                     },
                 ],
-                'country': 'ES',
-                'frequency': 2462,
-                'htmode': 'HT20',
-                'mode': '802.11s',
-                'noise': -95,
-                'signal': -61,
-                'ssid': 'Test Mesh',
-                'tx_power': 17,
+                "country": "ES",
+                "frequency": 2462,
+                "htmode": "HT20",
+                "mode": "802.11s",
+                "noise": -95,
+                "signal": -61,
+                "ssid": "Test Mesh",
+                "tx_power": 17,
             },
         }
     ],
-    'A4:BC:3F:AE:C7:0B': [
+    "A4:BC:3F:AE:C7:0B": [
         {
-            'mac': 'a4:bc:3f:ae:c7:0c',
-            'mtu': 1500,
-            'multicast': True,
-            'name': 'mesh0',
-            'txqueuelen': 1000,
-            'type': 'wireless',
-            'up': True,
-            'wireless': {
-                'channel': 11,
-                'clients': [
+            "mac": "a4:bc:3f:ae:c7:0c",
+            "mtu": 1500,
+            "multicast": True,
+            "name": "mesh0",
+            "txqueuelen": 1000,
+            "type": "wireless",
+            "up": True,
+            "wireless": {
+                "channel": 11,
+                "clients": [
                     {
-                        'auth': True,
-                        'authorized': True,
-                        'ht': True,
-                        'mac': '64:70:02:C3:03:B3',
-                        'mfp': False,
-                        'noise': -98,
-                        'signal': -58,
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'vht': False,
-                        'wmm': True,
-                        'mesh_llid': 20000,
-                        'mesh_plid': 25000,
-                        'mesh_non_peer_ps': 'ACTIVE',
+                        "auth": True,
+                        "authorized": True,
+                        "ht": True,
+                        "mac": "64:70:02:C3:03:B3",
+                        "mfp": False,
+                        "noise": -98,
+                        "signal": -58,
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "vht": False,
+                        "wmm": True,
+                        "mesh_llid": 20000,
+                        "mesh_plid": 25000,
+                        "mesh_non_peer_ps": "ACTIVE",
                     },
                     {
-                        'auth': True,
-                        'authorized': True,
-                        'ht': True,
-                        'mac': '2a:9a:fb:12:11:77',
-                        'mfp': False,
-                        'noise': -96,
-                        'signal': -60,
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'vht': False,
-                        'wmm': True,
-                        'mesh_llid': 19500,
-                        'mesh_plid': 24500,
-                        'mesh_non_peer_ps': 'ACTIVE',
+                        "auth": True,
+                        "authorized": True,
+                        "ht": True,
+                        "mac": "2a:9a:fb:12:11:77",
+                        "mfp": False,
+                        "noise": -96,
+                        "signal": -60,
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "vht": False,
+                        "wmm": True,
+                        "mesh_llid": 19500,
+                        "mesh_plid": 24500,
+                        "mesh_non_peer_ps": "ACTIVE",
                     },
                 ],
-                'country': 'ES',
-                'frequency': 2462,
-                'htmode': 'HT20',
-                'mode': '802.11s',
-                'noise': -95,
-                'signal': -56,
-                'ssid': 'Test Mesh',
-                'tx_power': 17,
+                "country": "ES",
+                "frequency": 2462,
+                "htmode": "HT20",
+                "mode": "802.11s",
+                "noise": -95,
+                "signal": -56,
+                "ssid": "Test Mesh",
+                "tx_power": 17,
             },
         }
     ],
-    '2A:9A:FB:12:11:76': [
+    "2A:9A:FB:12:11:76": [
         {
-            'mac': '2a:9a:fb:12:11:77',
-            'mtu': 1500,
-            'multicast': True,
-            'name': 'mesh0',
-            'txqueuelen': 1000,
-            'type': 'wireless',
-            'up': True,
-            'wireless': {
-                'channel': 11,
-                'clients': [
+            "mac": "2a:9a:fb:12:11:77",
+            "mtu": 1500,
+            "multicast": True,
+            "name": "mesh0",
+            "txqueuelen": 1000,
+            "type": "wireless",
+            "up": True,
+            "wireless": {
+                "channel": 11,
+                "clients": [
                     {
                         # Link properties
-                        'auth': True,
-                        'authorized': True,
-                        'noise': -92,
-                        'signal': -56,
+                        "auth": True,
+                        "authorized": True,
+                        "noise": -92,
+                        "signal": -56,
                         # Node properties
-                        'ht': True,
-                        'mfp': False,
-                        'vht': False,
-                        'wmm': True,
-                        'mac': 'a4:bc:3f:ae:c7:0c',
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'mesh_non_peer_ps': 'LISTEN',
+                        "ht": True,
+                        "mfp": False,
+                        "vht": False,
+                        "wmm": True,
+                        "mac": "a4:bc:3f:ae:c7:0c",
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "mesh_non_peer_ps": "LISTEN",
                     },
                     {
-                        'mac': '0a:cc:ae:34:ff:3d',
-                        'wps': False,
-                        'wds': False,
-                        'ht': True,
-                        'preauth': False,
-                        'assoc': True,
-                        'authorized': True,
-                        'vht': False,
-                        'wmm': False,
-                        'aid': 1,
-                        'mfp': False,
-                        'auth': True,
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'signature': 'test_signature',
-                        'mesh_plink': 'LISTEN',
+                        "mac": "0a:cc:ae:34:ff:3d",
+                        "wps": False,
+                        "wds": False,
+                        "ht": True,
+                        "preauth": False,
+                        "assoc": True,
+                        "authorized": True,
+                        "vht": False,
+                        "wmm": False,
+                        "aid": 1,
+                        "mfp": False,
+                        "auth": True,
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "signature": "test_signature",
+                        "mesh_plink": "LISTEN",
                     },
                 ],
-                'country': 'ES',
-                'frequency': 2462,
-                'htmode': 'HT20',
-                'mode': '802.11s',
-                'noise': -95,
-                'signal': -64,
-                'ssid': 'Test Mesh',
-                'tx_power': 17,
+                "country": "ES",
+                "frequency": 2462,
+                "htmode": "HT20",
+                "mode": "802.11s",
+                "noise": -95,
+                "signal": -64,
+                "ssid": "Test Mesh",
+                "tx_power": 17,
             },
         },
         {
-            'addresses': [
+            "addresses": [
                 {
-                    'address': '192.168.1.1',
-                    'family': 'ipv4',
-                    'mask': 24,
-                    'proto': 'static',
+                    "address": "192.168.1.1",
+                    "family": "ipv4",
+                    "mask": 24,
+                    "proto": "static",
                 },
             ],
-            'bridge_members': ['eth0.1', 'mesh0'],
-            'mac': '2a:9a:fb:12:11:76',
-            'mtu': 1500,
-            'multicast': True,
-            'name': 'br-lan',
-            'speed': '-1F',
-            'stp': False,
-            'txqueuelen': 1000,
-            'type': 'bridge',
-            'up': True,
+            "bridge_members": ["eth0.1", "mesh0"],
+            "mac": "2a:9a:fb:12:11:76",
+            "mtu": 1500,
+            "multicast": True,
+            "name": "br-lan",
+            "speed": "-1F",
+            "stp": False,
+            "txqueuelen": 1000,
+            "type": "bridge",
+            "up": True,
         },
         {
-            'name': 'wlan0',
-            'type': 'wireless',
-            'up': True,
-            'mac': '2a:9a:fb:12:11:78',
-            'txqueuelen': 1000,
-            'multicast': True,
-            'mtu': 1500,
-            'wireless': {
-                'frequency': 2437,
-                'mode': 'access_point',
-                'signal': -29,
-                'tx_power': 6,
-                'channel': 6,
-                'ssid': 'testnet',
-                'noise': -95,
-                'country': 'US',
-                'htmode': 'HT20',
-                'clients': [
+            "name": "wlan0",
+            "type": "wireless",
+            "up": True,
+            "mac": "2a:9a:fb:12:11:78",
+            "txqueuelen": 1000,
+            "multicast": True,
+            "mtu": 1500,
+            "wireless": {
+                "frequency": 2437,
+                "mode": "access_point",
+                "signal": -29,
+                "tx_power": 6,
+                "channel": 6,
+                "ssid": "testnet",
+                "noise": -95,
+                "country": "US",
+                "htmode": "HT20",
+                "clients": [
                     {
-                        'mac': '00:ee:ad:34:f5:3b',
-                        'wps': False,
-                        'wds': False,
-                        'ht': True,
-                        'preauth': False,
-                        'assoc': True,
-                        'authorized': True,
-                        'vht': False,
-                        'wmm': True,
-                        'aid': 1,
-                        'mfp': False,
-                        'auth': True,
-                        'vendor': 'TP-LINK TECHNOLOGIES CO.,LTD.',
-                        'signature': 'test_signature',
+                        "mac": "00:ee:ad:34:f5:3b",
+                        "wps": False,
+                        "wds": False,
+                        "ht": True,
+                        "preauth": False,
+                        "assoc": True,
+                        "authorized": True,
+                        "vht": False,
+                        "wmm": True,
+                        "aid": 1,
+                        "mfp": False,
+                        "auth": True,
+                        "vendor": "TP-LINK TECHNOLOGIES CO.,LTD.",
+                        "signature": "test_signature",
                     },
                 ],
             },
@@ -223,32 +223,32 @@
 }
 
 SINGLE_NODE_MESH_DATA = {
-    '64:70:02:C3:03:B2': [
+    "64:70:02:C3:03:B2": [
         {
-            'mac': '64:70:02:c3:03:b3',
-            'mtu': 1500,
-            'multicast': True,
-            'name': 'mesh0',
-            'txqueuelen': 1000,
-            'type': 'wireless',
-            'up': True,
-            'wireless': {
-                'channel': 11,
-                'clients': [],
-                'country': 'ES',
-                'frequency': 2462,
-                'htmode': 'HT20',
-                'mode': '802.11s',
-                'noise': -95,
-                'signal': -61,
-                'ssid': 'Test Mesh',
-                'tx_power': 17,
-                'mesh_llid': 19751,
-                'mesh_local_ps': 'ACTIVE',
-                'mesh_non_peer_ps': 'ACTIVE',
-                'mesh_peer_ps': 'ACTIVE',
-                'mesh_plid': 24413,
-                'mesh_plink': 'ESTAB',
+            "mac": "64:70:02:c3:03:b3",
+            "mtu": 1500,
+            "multicast": True,
+            "name": "mesh0",
+            "txqueuelen": 1000,
+            "type": "wireless",
+            "up": True,
+            "wireless": {
+                "channel": 11,
+                "clients": [],
+                "country": "ES",
+                "frequency": 2462,
+                "htmode": "HT20",
+                "mode": "802.11s",
+                "noise": -95,
+                "signal": -61,
+                "ssid": "Test Mesh",
+                "tx_power": 17,
+                "mesh_llid": 19751,
+                "mesh_local_ps": "ACTIVE",
+                "mesh_non_peer_ps": "ACTIVE",
+                "mesh_peer_ps": "ACTIVE",
+                "mesh_plid": 24413,
+                "mesh_plink": "ESTAB",
             },
         }
     ],
diff --git a/openwisp_network_topology/integrations/device/tests/test_integration.py b/openwisp_network_topology/integrations/device/tests/test_integration.py
index 833c5767..19b5366e 100644
--- a/openwisp_network_topology/integrations/device/tests/test_integration.py
+++ b/openwisp_network_topology/integrations/device/tests/test_integration.py
@@ -24,16 +24,16 @@
 from ..base.models import logger as models_logger
 from ..base.models import trigger_device_checks_path
 
-Node = swapper.load_model('topology', 'Node')
-Link = swapper.load_model('topology', 'Link')
-Topology = swapper.load_model('topology', 'Topology')
-DeviceNode = swapper.load_model('topology_device', 'DeviceNode')
-WifiMesh = swapper.load_model('topology_device', 'WifiMesh')
-Device = swapper.load_model('config', 'Device')
-Template = swapper.load_model('config', 'Template')
-Vpn = swapper.load_model('config', 'Template')
-Organization = swapper.load_model('openwisp_users', 'Organization')
-Cert = swapper.load_model('pki', 'Cert')
+Node = swapper.load_model("topology", "Node")
+Link = swapper.load_model("topology", "Link")
+Topology = swapper.load_model("topology", "Topology")
+DeviceNode = swapper.load_model("topology_device", "DeviceNode")
+WifiMesh = swapper.load_model("topology_device", "WifiMesh")
+Device = swapper.load_model("config", "Device")
+Template = swapper.load_model("config", "Template")
+Vpn = swapper.load_model("config", "Template")
+Organization = swapper.load_model("openwisp_users", "Organization")
+Cert = swapper.load_model("pki", "Cert")
 
 
 class Base(
@@ -47,25 +47,25 @@ class Base(
 ):
     topology_model = Topology
     node_model = Node
-    _ZT_SERVICE_REQUESTS = 'openwisp_controller.config.api.zerotier_service.requests'
-    _ZT_GENERATE_IDENTITY_SUBPROCESS = 'openwisp_controller.config.base.vpn.subprocess'
+    _ZT_SERVICE_REQUESTS = "openwisp_controller.config.api.zerotier_service.requests"
+    _ZT_GENERATE_IDENTITY_SUBPROCESS = "openwisp_controller.config.base.vpn.subprocess"
 
     def _init_test_node(
         self,
         topology,
         addresses=None,
-        label='test',
+        label="test",
         common_name=None,
         create=True,
     ):
         if not addresses:
-            addresses = ['netjson_id']
+            addresses = ["netjson_id"]
         node = Node(
             organization=topology.organization,
             topology=topology,
             label=label,
             addresses=addresses,
-            properties={'common_name': common_name},
+            properties={"common_name": common_name},
         )
         if create:
             node.full_clean()
@@ -74,22 +74,22 @@ def _init_test_node(
 
     def _init_wireguard_test_node(self, topology, addresses=[], create=True, **kwargs):
         if not addresses:
-            addresses = ['public_key']
+            addresses = ["public_key"]
         properties = {
-            'preshared_key': None,
-            'endpoint': None,
-            'latest_handsake': '0',
-            'transfer_rx': '0',
-            'transfer_tx': '0',
-            'persistent_keepalive': 'off',
-            'allowed_ips': ['10.0.0.2/32'],
+            "preshared_key": None,
+            "endpoint": None,
+            "latest_handsake": "0",
+            "transfer_rx": "0",
+            "transfer_tx": "0",
+            "persistent_keepalive": "off",
+            "allowed_ips": ["10.0.0.2/32"],
         }
         properties.update(kwargs)
-        allowed_ips = properties.get('allowed_ips')
+        allowed_ips = properties.get("allowed_ips")
         node = Node(
             organization=topology.organization,
             topology=topology,
-            label=','.join(allowed_ips),
+            label=",".join(allowed_ips),
             addresses=addresses,
             properties=properties,
         )
@@ -99,17 +99,17 @@ def _init_wireguard_test_node(self, topology, addresses=[], create=True, **kwarg
         return node
 
     def _init_zerotier_test_node(
-        self, topology, addresses=None, label='test', zt_member_id=None, create=True
+        self, topology, addresses=None, label="test", zt_member_id=None, create=True
     ):
         if not addresses:
-            addresses = [self._TEST_ZT_MEMBER_CONFIG['address']]
+            addresses = [self._TEST_ZT_MEMBER_CONFIG["address"]]
         node = Node(
             organization=topology.organization,
             topology=topology,
             label=label,
             addresses=addresses,
             # zt peer address is `zt_memeber_id`
-            properties={'address': zt_member_id},
+            properties={"address": zt_member_id},
         )
         if create:
             node.full_clean()
@@ -141,7 +141,7 @@ def _create_zerotier_test_env(self, mock_requests, mock_subprocess, parser):
             self._get_mock_response(200),
         ]
         mock_stdout = mock.MagicMock()
-        mock_stdout.stdout.decode.return_value = self._TEST_ZT_MEMBER_CONFIG['identity']
+        mock_stdout.stdout.decode.return_value = self._TEST_ZT_MEMBER_CONFIG["identity"]
         mock_subprocess.run.return_value = mock_stdout
         org = self._get_org()
         device, _, _ = self._create_zerotier_vpn_template()
@@ -152,19 +152,19 @@ def _create_zerotier_test_env(self, mock_requests, mock_subprocess, parser):
 
     def _create_test_env(self, parser):
         organization = self._get_org()
-        vpn = self._create_vpn(name='test VPN', organization=organization)
+        vpn = self._create_vpn(name="test VPN", organization=organization)
         self._create_template(
-            name='VPN',
-            type='vpn',
+            name="VPN",
+            type="vpn",
             vpn=vpn,
             config=vpn.auto_client(),
             default=True,
             organization=organization,
         )
-        vpn2 = self._create_vpn(name='test VPN2', ca=vpn.ca, organization=organization)
+        vpn2 = self._create_vpn(name="test VPN2", ca=vpn.ca, organization=organization)
         self._create_template(
-            name='VPN2',
-            type='vpn',
+            name="VPN2",
+            type="vpn",
             vpn=vpn2,
             config=vpn.auto_client(),
             default=True,
@@ -179,9 +179,9 @@ def _create_test_env(self, parser):
 
 class TestControllerIntegration(Base, TransactionTestCase):
     def test_auto_create_openvpn(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         self.assertEqual(DeviceNode.objects.count(), 0)
-        with self.subTest('assert number of queries'):
+        with self.subTest("assert number of queries"):
             with self.assertNumQueries(15):
                 node = self._init_test_node(topology, common_name=cert.common_name)
         self.assertEqual(DeviceNode.objects.count(), 1)
@@ -189,27 +189,27 @@ def test_auto_create_openvpn(self):
         self.assertEqual(device_node.device, device)
         self.assertEqual(device_node.node, node)
 
-        with self.subTest('not run on save'):
-            with mock.patch.object(transaction, 'on_commit') as on_commit:
+        with self.subTest("not run on save"):
+            with mock.patch.object(transaction, "on_commit") as on_commit:
                 node.save()
                 on_commit.assert_not_called()
 
     def test_auto_create_openvpn_failures(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
 
-        with self.subTest('common_name not present'):
+        with self.subTest("common_name not present"):
             self._init_test_node(topology)
             self.assertFalse(DeviceNode.objects.exists())
 
-        with self.subTest('cert does not exist'):
-            self._init_test_node(topology, common_name='missing')
+        with self.subTest("cert does not exist"):
+            self._init_test_node(topology, common_name="missing")
             self.assertFalse(DeviceNode.objects.exists())
 
-        with self.subTest('exception during save'):
+        with self.subTest("exception during save"):
             with mock.patch.object(
-                DeviceNode, 'save', side_effect=Exception('test')
+                DeviceNode, "save", side_effect=Exception("test")
             ) as save:
-                with mock.patch.object(models_logger, 'exception') as logger_exception:
+                with mock.patch.object(models_logger, "exception") as logger_exception:
                     self._init_test_node(topology, common_name=cert.common_name)
                     save.assert_called_once()
                     logger_exception.assert_called_once()
@@ -217,42 +217,42 @@ def test_auto_create_openvpn_failures(self):
 
     def test_auto_create_wireguard(self):
         topology, device = self._create_wireguard_test_env(
-            parser='netdiff.WireguardParser'
+            parser="netdiff.WireguardParser"
         )
         self.assertEqual(DeviceNode.objects.count(), 0)
-        with self.subTest('return if node has no allowed ips'):
+        with self.subTest("return if node has no allowed ips"):
             node = self._init_wireguard_test_node(topology, allowed_ips=[])
             self.assertEqual(DeviceNode.objects.count(), 0)
-        with self.subTest('handle error if node has bogus allowed ips'):
+        with self.subTest("handle error if node has bogus allowed ips"):
             try:
-                node = self._init_wireguard_test_node(topology, allowed_ips=['invalid'])
+                node = self._init_wireguard_test_node(topology, allowed_ips=["invalid"])
             except ValueError:
-                self.fail('ValueError raised')
-        with self.subTest('assert number of queries'):
+                self.fail("ValueError raised")
+        with self.subTest("assert number of queries"):
             with self.assertNumQueries(15):
                 node = self._init_wireguard_test_node(topology)
         self.assertEqual(DeviceNode.objects.count(), 1)
         device_node = DeviceNode.objects.first()
         self.assertEqual(device_node.device, device)
         self.assertEqual(device_node.node, node)
-        with self.subTest('do not raise Exception on link status changed'):
+        with self.subTest("do not raise Exception on link status changed"):
             try:
                 target_node = self._init_wireguard_test_node(topology)
                 link = Link(
                     topology=node.topology, source=node, target=target_node, cost=0
                 )
                 link.save()
-                link.status = 'down'
-                link.save(update_fields=['status'])
+                link.status = "down"
+                link.save(update_fields=["status"])
             except KeyError:
-                self.fail('KeyError raised')
+                self.fail("KeyError raised")
 
     def test_auto_create_zerotier(self):
         topology, device, zerotier_member_id = self._create_zerotier_test_env(
-            parser='netdiff.ZeroTierParser'
+            parser="netdiff.ZeroTierParser"
         )
         self.assertEqual(DeviceNode.objects.count(), 0)
-        with self.subTest('assert number of queries'):
+        with self.subTest("assert number of queries"):
             with self.assertNumQueries(15):
                 node = self._init_zerotier_test_node(
                     topology, zt_member_id=zerotier_member_id
@@ -262,29 +262,29 @@ def test_auto_create_zerotier(self):
         self.assertEqual(device_node.device, device)
         self.assertEqual(device_node.node, node)
 
-        with self.subTest('not run on save'):
-            with mock.patch.object(transaction, 'on_commit') as on_commit:
+        with self.subTest("not run on save"):
+            with mock.patch.object(transaction, "on_commit") as on_commit:
                 node.save()
                 on_commit.assert_not_called()
 
     def test_auto_create_zerotier_failures(self):
         topology, device, zerotier_member_id = self._create_zerotier_test_env(
-            parser='netdiff.ZeroTierParser'
+            parser="netdiff.ZeroTierParser"
         )
 
-        with self.subTest('zerotier_member_id not present'):
+        with self.subTest("zerotier_member_id not present"):
             self._init_zerotier_test_node(topology)
             self.assertFalse(DeviceNode.objects.exists())
 
-        with self.subTest('zerotier_member_id does not exist'):
-            self._init_zerotier_test_node(topology, zt_member_id='non_existent_id')
+        with self.subTest("zerotier_member_id does not exist"):
+            self._init_zerotier_test_node(topology, zt_member_id="non_existent_id")
             self.assertFalse(DeviceNode.objects.exists())
 
-        with self.subTest('exception during save'):
+        with self.subTest("exception during save"):
             with mock.patch.object(
-                DeviceNode, 'save', side_effect=Exception('test')
+                DeviceNode, "save", side_effect=Exception("test")
             ) as save:
-                with mock.patch.object(models_logger, 'exception') as logger_exception:
+                with mock.patch.object(models_logger, "exception") as logger_exception:
                     self._init_zerotier_test_node(
                         topology, zt_member_id=zerotier_member_id
                     )
@@ -293,15 +293,15 @@ def test_auto_create_zerotier_failures(self):
                     self.assertEqual(DeviceNode.objects.count(), 0)
 
     def test_filter_by_link(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
 
-        with self.subTest('empty result'):
+        with self.subTest("empty result"):
             node = self._init_test_node(topology, common_name=cert.common_name)
             self.assertFalse(DeviceNode.filter_by_link(Link()).exists())
 
-        with self.subTest('non empty result'):
+        with self.subTest("non empty result"):
             node2 = self._init_test_node(
-                topology, addresses=['netjson_id2'], label='test2'
+                topology, addresses=["netjson_id2"], label="test2"
             )
             link = Link(
                 source=node,
@@ -315,15 +315,15 @@ def test_filter_by_link(self):
             self.assertTrue(DeviceNode.filter_by_link(link).exists())
 
     def test_link_down_openvpn(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         node = self._init_test_node(topology, common_name=cert.common_name)
-        node2 = self._init_test_node(topology, addresses=['netjson_id2'], label='test2')
-        device.management_ip = '10.0.0.8'
+        node2 = self._init_test_node(topology, addresses=["netjson_id2"], label="test2")
+        device.management_ip = "10.0.0.8"
         device.save()
         link = Link(
             source=node,
             target=node2,
-            status='up',
+            status="up",
             topology=topology,
             organization=topology.organization,
             cost=1,
@@ -331,23 +331,23 @@ def test_link_down_openvpn(self):
         link.full_clean()
         link.save()
         with self.assertNumQueries(6):
-            link.status = 'down'
+            link.status = "down"
             link.save()
         device.refresh_from_db()
         self.assertIsNone(device.management_ip)
 
     def test_link_up_openvpn(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         node = self._init_test_node(
-            topology, addresses=['netjson_id', '10.0.0.2'], common_name=cert.common_name
+            topology, addresses=["netjson_id", "10.0.0.2"], common_name=cert.common_name
         )
-        node2 = self._init_test_node(topology, addresses=['netjson_id2'], label='test2')
+        node2 = self._init_test_node(topology, addresses=["netjson_id2"], label="test2")
         device.management_ip = None
         device.save()
         link = Link(
             source=node,
             target=node2,
-            status='down',
+            status="down",
             topology=topology,
             organization=topology.organization,
             cost=1,
@@ -355,26 +355,26 @@ def test_link_up_openvpn(self):
         link.full_clean()
         link.save()
         with self.assertNumQueries(6):
-            link.status = 'up'
+            link.status = "up"
             link.save()
         device.refresh_from_db()
-        self.assertEqual(device.management_ip, '10.0.0.2')
+        self.assertEqual(device.management_ip, "10.0.0.2")
 
-    @mock.patch.object(models_logger, 'warning')
+    @mock.patch.object(models_logger, "warning")
     def test_link_up_openvpn_failure(self, logger_warning):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         node = self._init_test_node(
             topology,
-            addresses=['netjson_id', 'not_an_ip'],
+            addresses=["netjson_id", "not_an_ip"],
             common_name=cert.common_name,
         )
-        node2 = self._init_test_node(topology, addresses=['netjson_id2'], label='test2')
+        node2 = self._init_test_node(topology, addresses=["netjson_id2"], label="test2")
         device.management_ip = None
         device.save()
         link = Link(
             source=node,
             target=node2,
-            status='down',
+            status="down",
             topology=topology,
             organization=topology.organization,
             cost=1,
@@ -382,64 +382,64 @@ def test_link_up_openvpn_failure(self, logger_warning):
         link.full_clean()
         link.save()
 
-        with self.subTest('Test invalid addresses'):
-            link.status = 'up'
+        with self.subTest("Test invalid addresses"):
+            link.status = "up"
             link.save()
             logger_warning.assert_called_once()
             logger_warning.assert_called_with(
-                'ValueError raised while processing addresses: netjson_id, not_an_ip'
+                "ValueError raised while processing addresses: netjson_id, not_an_ip"
             )
 
-        link.status = 'down'
+        link.status = "down"
         link.save()
         logger_warning.reset_mock()
 
-        with self.subTest('Test disconnected nodes'):
-            node.addresses = ['10.0.0.1']
+        with self.subTest("Test disconnected nodes"):
+            node.addresses = ["10.0.0.1"]
             node.save()
-            link.status = 'up'
+            link.status = "up"
             link.save()
             logger_warning.assert_called_once()
             logger_warning.assert_called_with(
-                'IndexError raised while processing addresses: 10.0.0.1'
+                "IndexError raised while processing addresses: 10.0.0.1"
             )
 
         device.refresh_from_db()
         self.assertIsNone(device.management_ip)
 
     def test_node_label_override(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         node = self._init_test_node(topology, common_name=cert.common_name)
         node.refresh_from_db()
         self.assertEqual(node.get_name(), device.name)
 
     def test_topology_json(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         self._init_test_node(topology, common_name=cert.common_name)
-        with self.subTest('assert number of queries'):
+        with self.subTest("assert number of queries"):
             with self.assertNumQueries(2):
                 json = topology.json(dict=True)
-        self.assertEqual(json['nodes'][0]['label'], device.name)
+        self.assertEqual(json["nodes"][0]["label"], device.name)
 
     def test_create_device_nodes_command(self):
-        topology, _, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
-        properties = {'common_name': cert.common_name}
+        topology, _, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
+        properties = {"common_name": cert.common_name}
         n = self._create_node(topology=topology, properties=properties)
         DeviceNode.objects.all().delete()
-        call_command('create_device_nodes')
+        call_command("create_device_nodes")
         qs = DeviceNode.objects.filter(node=n)
         self.assertEqual(qs.count(), 1)
 
     def test_shared_topology_org_devices(self):
-        org1 = self._create_org(name='org1')
-        org2 = self._create_org(name='org2')
+        org1 = self._create_org(name="org1")
+        org2 = self._create_org(name="org2")
         shared_topology = self._create_topology(
-            organization=None, parser='netdiff.OpenvpnParser'
+            organization=None, parser="netdiff.OpenvpnParser"
         )
-        shared_vpn = self._create_vpn(name='test VPN', organization=None)
+        shared_vpn = self._create_vpn(name="test VPN", organization=None)
         self._create_template(
-            name='VPN',
-            type='vpn',
+            name="VPN",
+            type="vpn",
             vpn=shared_vpn,
             config=shared_vpn.auto_client(),
             default=True,
@@ -457,18 +457,18 @@ def test_shared_topology_org_devices(self):
         )
 
         openvpn_status = (
-            'OpenVPN CLIENT LIST\n'
-            'Updated,Sun Oct  8 19:46:06 2017\n'
-            'Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since\n'
-            f'{org1_cert_common_name},87.7.9.213:56857,417209,6046898,Sun Oct  8 08:39:11 2017\n'
-            f'{org2_cert_common_name},2.226.154.66:52091,6020304,444463,Sun Oct  8 08:39:10 2017\n'
-            'ROUTING TABLE\n'
-            'Virtual Address,Common Name,Real Address,Last Ref\n'
-            f'9e:c2:f2:55:f4:33,{org1_cert_common_name},87.7.9.213:56857,Sun Oct  8 19:45:37 2017\n'
-            f'46:8a:69:e7:46:24,{org2_cert_common_name},2.226.154.66:52091,Sun Oct  8 19:45:37 2017\n'
-            'GLOBAL STATS\n'
-            'Max bcast/mcast queue length,6\n'
-            'END'
+            "OpenVPN CLIENT LIST\n"
+            "Updated,Sun Oct  8 19:46:06 2017\n"
+            "Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since\n"
+            f"{org1_cert_common_name},87.7.9.213:56857,417209,6046898,Sun Oct  8 08:39:11 2017\n"
+            f"{org2_cert_common_name},2.226.154.66:52091,6020304,444463,Sun Oct  8 08:39:10 2017\n"
+            "ROUTING TABLE\n"
+            "Virtual Address,Common Name,Real Address,Last Ref\n"
+            f"9e:c2:f2:55:f4:33,{org1_cert_common_name},87.7.9.213:56857,Sun Oct  8 19:45:37 2017\n"
+            f"46:8a:69:e7:46:24,{org2_cert_common_name},2.226.154.66:52091,Sun Oct  8 19:45:37 2017\n"
+            "GLOBAL STATS\n"
+            "Max bcast/mcast queue length,6\n"
+            "END"
         )
         shared_topology.receive(openvpn_status)
         self.assertEqual(DeviceNode.objects.count(), 2)
@@ -480,25 +480,25 @@ def test_shared_topology_org_devices(self):
 
 class TestMonitoringIntegration(Base, TransactionTestCase):
     @mock.patch(
-        'openwisp_monitoring.device.apps.DeviceMonitoringConfig.connect_device_signals'
+        "openwisp_monitoring.device.apps.DeviceMonitoringConfig.connect_device_signals"
     )
-    @mock.patch('openwisp_monitoring.db.timeseries_db.create_database')
-    @mock.patch('openwisp_monitoring.device.utils.manage_short_retention_policy')
-    @mock.patch('openwisp_monitoring.device.utils.manage_default_retention_policy')
-    @mock.patch('openwisp_monitoring.device.exportable._exportable_fields', [])
-    @mock.patch('openwisp_notifications.types.NOTIFICATION_TYPES', dict())
+    @mock.patch("openwisp_monitoring.db.timeseries_db.create_database")
+    @mock.patch("openwisp_monitoring.device.utils.manage_short_retention_policy")
+    @mock.patch("openwisp_monitoring.device.utils.manage_default_retention_policy")
+    @mock.patch("openwisp_monitoring.device.exportable._exportable_fields", [])
+    @mock.patch("openwisp_notifications.types.NOTIFICATION_TYPES", dict())
     def test_monitoring_integration(self, *args):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         node = self._init_test_node(
-            topology, addresses=['netjson_id', '10.0.0.2'], common_name=cert.common_name
+            topology, addresses=["netjson_id", "10.0.0.2"], common_name=cert.common_name
         )
-        node2 = self._init_test_node(topology, addresses=['netjson_id2'], label='test2')
+        node2 = self._init_test_node(topology, addresses=["netjson_id2"], label="test2")
         device.management_ip = None
         device.save()
         link = Link(
             source=node,
             target=node2,
-            status='up',
+            status="up",
             topology=topology,
             organization=topology.organization,
             cost=1,
@@ -510,43 +510,43 @@ def test_monitoring_integration(self, *args):
         MENU.clear()
         # needed for monitoring
         trigger_device_checks = import_string(trigger_device_checks_path)
-        with mock.patch.object(trigger_device_checks, 'delay') as mocked_task:
+        with mock.patch.object(trigger_device_checks, "delay") as mocked_task:
             with self.modify_settings(
                 INSTALLED_APPS={
-                    'append': [
-                        'openwisp_controller.connection',
-                        'openwisp_controller.geo',
-                        'openwisp_monitoring.monitoring',
-                        'openwisp_monitoring.device',
-                        'openwisp_monitoring.check',
-                        'openwisp_notifications',
+                    "append": [
+                        "openwisp_controller.connection",
+                        "openwisp_controller.geo",
+                        "openwisp_monitoring.monitoring",
+                        "openwisp_monitoring.device",
+                        "openwisp_monitoring.check",
+                        "openwisp_notifications",
                     ]
                 }
             ):
-                link.status = 'down'
+                link.status = "down"
                 link.save()
             mocked_task.assert_called_once()
             mocked_task.assert_called_with(device.pk, recovery=False)
 
 
 class TestAdmin(Base, TransactionTestCase):
-    module = 'openwisp_network_topology'
-    app_label = 'topology'
+    module = "openwisp_network_topology"
+    app_label = "topology"
     topology_model = Topology
     link_model = Link
     node_model = Node
     user_model = get_user_model()
-    fixtures = ['test_users.json']
-    api_urls_path = 'api.urls'
+    fixtures = ["test_users.json"]
+    api_urls_path = "api.urls"
 
     @property
     def prefix(self):
-        return 'admin:{0}'.format(self.app_label)
+        return "admin:{0}".format(self.app_label)
 
     def setUp(self):
-        topology, device, cert = self._create_test_env(parser='netdiff.OpenvpnParser')
+        topology, device, cert = self._create_test_env(parser="netdiff.OpenvpnParser")
         node1 = self._init_test_node(topology, common_name=cert.common_name)
-        node2 = self._init_test_node(topology, addresses=['netjson_id2'], label='test2')
+        node2 = self._init_test_node(topology, addresses=["netjson_id2"], label="test2")
         link = Link(
             source=node1,
             target=node2,
@@ -557,15 +557,15 @@ def setUp(self):
         link.full_clean()
         link.save()
         self._create_link(topology=topology, source=node1, target=node2)
-        self.client.force_login(self.user_model.objects.get(username='admin'))
+        self.client.force_login(self.user_model.objects.get(username="admin"))
 
     def test_node_change_list_queries(self):
-        path = reverse('{0}_node_changelist'.format(self.prefix))
+        path = reverse("{0}_node_changelist".format(self.prefix))
         with self.assertNumQueries(5):
             self.client.get(path)
 
     def test_link_change_list_queries(self):
-        path = reverse('{0}_link_changelist'.format(self.prefix))
+        path = reverse("{0}_link_changelist".format(self.prefix))
         with self.assertNumQueries(5):
             self.client.get(path)
 
@@ -586,30 +586,30 @@ def test_link_node_different_topology(self):
         with self.assertRaises(ValidationError) as context:
             # Raises ValidationError if link belongs to diff topologies
             link.full_clean()
-        self.assertIn('source', context.exception.error_dict)
-        self.assertIn('target', context.exception.error_dict)
+        self.assertIn("source", context.exception.error_dict)
+        self.assertIn("target", context.exception.error_dict)
 
     def test_link_update_status(self):
         t = Topology.objects.first()
-        n1 = self._create_node(label='node1org1', topology=t)
-        n2 = self._create_node(label='node2org1', topology=t)
+        n1 = self._create_node(label="node1org1", topology=t)
+        n2 = self._create_node(label="node2org1", topology=t)
         link = self._create_link(topology=t, source=n1, target=n2)
-        path = reverse('{0}_link_change'.format(self.prefix), args=[link.pk])
+        path = reverse("{0}_link_change".format(self.prefix), args=[link.pk])
         response = self.client.post(
             path,
             data={
-                'topology': str(t.pk),
-                'organization': str(t.organization_id),
-                'source': str(n1.id),
-                'target': str(n2.id),
-                'cost': '1.0',
-                'status': 'down',
+                "topology": str(t.pk),
+                "organization": str(t.organization_id),
+                "source": str(n1.id),
+                "target": str(n2.id),
+                "cost": "1.0",
+                "status": "down",
             },
             follow=True,
         )
         self.assertEqual(response.status_code, 200)
         link.refresh_from_db()
-        self.assertEqual(link.status, 'down')
+        self.assertEqual(link.status, "down")
 
     def test_topology_admin(self):
         """
@@ -623,11 +623,11 @@ def test_topology_admin(self):
         """
         topology = Topology.objects.first()
         response = self.client.get(
-            reverse(f'{self.prefix}_topology_change', args=[topology.id])
+            reverse(f"{self.prefix}_topology_change", args=[topology.id])
         )
-        self.assertNotContains(response, 'Wifi mesh')
+        self.assertNotContains(response, "Wifi mesh")
 
     def test_topology_get_name_desc(self):
-        response = self.client.get(reverse(f'{self.prefix}_node_changelist'))
-        self.assertNotContains(response, '<span>Get name</span>', html=True)
-        self.assertContains(response, '<span>Label</span>', html=True)
+        response = self.client.get(reverse(f"{self.prefix}_node_changelist"))
+        self.assertNotContains(response, "<span>Get name</span>", html=True)
+        self.assertContains(response, "<span>Label</span>", html=True)
diff --git a/openwisp_network_topology/integrations/device/tests/test_wifi_mesh.py b/openwisp_network_topology/integrations/device/tests/test_wifi_mesh.py
index c0acf1d8..5236e92d 100644
--- a/openwisp_network_topology/integrations/device/tests/test_wifi_mesh.py
+++ b/openwisp_network_topology/integrations/device/tests/test_wifi_mesh.py
@@ -15,17 +15,17 @@
 from . import SIMPLE_MESH_DATA, SINGLE_NODE_MESH_DATA
 from .utils import TopologyTestMixin
 
-Node = swapper.load_model('topology', 'Node')
-Link = swapper.load_model('topology', 'Link')
-Topology = swapper.load_model('topology', 'Topology')
-DeviceNode = swapper.load_model('topology_device', 'DeviceNode')
-WifiMesh = swapper.load_model('topology_device', 'WifiMesh')
-Device = swapper.load_model('config', 'Device')
+Node = swapper.load_model("topology", "Node")
+Link = swapper.load_model("topology", "Link")
+Topology = swapper.load_model("topology", "Topology")
+DeviceNode = swapper.load_model("topology_device", "DeviceNode")
+WifiMesh = swapper.load_model("topology_device", "WifiMesh")
+Device = swapper.load_model("config", "Device")
 
 
-@tag('wifi_mesh')
+@tag("wifi_mesh")
 class TestWifiMeshIntegration(TopologyTestMixin, TransactionTestCase):
-    app_label = 'topology'
+    app_label = "topology"
 
     def setUp(self):
         super().setUp()
@@ -33,7 +33,7 @@ def setUp(self):
 
     @property
     def prefix(self):
-        return 'admin:{0}'.format(self.app_label)
+        return "admin:{0}".format(self.app_label)
 
     def _populate_mesh(self, data):
         org = self._get_org()
@@ -42,27 +42,27 @@ def _populate_mesh(self, data):
             device = self._create_device(name=mac, mac_address=mac, organization=org)
             devices.append(device)
             response = self.client.post(
-                '{0}?key={1}&time={2}'.format(
-                    reverse('monitoring:api_device_metric', args=[device.id]),
+                "{0}?key={1}&time={2}".format(
+                    reverse("monitoring:api_device_metric", args=[device.id]),
                     device.key,
-                    now().utcnow().strftime('%d-%m-%Y_%H:%M:%S.%f'),
+                    now().utcnow().strftime("%d-%m-%Y_%H:%M:%S.%f"),
                 ),
                 data=json.dumps(
                     {
-                        'type': 'DeviceMonitoring',
-                        'interfaces': interfaces,
+                        "type": "DeviceMonitoring",
+                        "interfaces": interfaces,
                     }
                 ),
-                content_type='application/json',
+                content_type="application/json",
             )
             self.assertEqual(response.status_code, 200)
         create_mesh_topology.delay(organization_ids=(org.id,))
         return devices, org
 
-    @patch.object(app_settings, 'WIFI_MESH_INTEGRATION', False)
+    @patch.object(app_settings, "WIFI_MESH_INTEGRATION", False)
     def test_wifi_mesh_integration_disabled(self):
         with self.subTest('Test calling "create_mesh_topology" task'):
-            with patch.object(WifiMesh, 'create_topology') as mocked:
+            with patch.object(WifiMesh, "create_topology") as mocked:
                 _, org = self._populate_mesh(SIMPLE_MESH_DATA)
                 self.assertEqual(Topology.objects.count(), 0)
                 mocked.assert_not_called()
@@ -71,7 +71,7 @@ def test_wifi_mesh_integration_disabled(self):
         # previous one fails.
         Topology.objects.all().delete()
 
-        with self.subTest('Test calling WifiMesh.create_topology'):
+        with self.subTest("Test calling WifiMesh.create_topology"):
             with self.assertRaises(ImproperlyConfigured) as error:
                 WifiMesh.create_topology(
                     organization_ids=[org.id], discard_older_data_time=360
@@ -86,7 +86,7 @@ def test_simple_mesh(self):
         self.assertEqual(Topology.objects.filter(organization=org).count(), 1)
         topology = Topology.objects.filter(organization=org).first()
         self.assertEqual(
-            WifiMesh.objects.filter(topology=topology, mesh_id='Test Mesh@11').count(),
+            WifiMesh.objects.filter(topology=topology, mesh_id="Test Mesh@11").count(),
             1,
         )
         self.assertEqual(
@@ -124,17 +124,17 @@ def test_simple_mesh(self):
 
         # Test DeviceNode creation logic is not executed when the create_topology
         # is executed again
-        with patch.object(DeviceNode, 'auto_create') as mocked_auto_create:
+        with patch.object(DeviceNode, "auto_create") as mocked_auto_create:
             create_mesh_topology.delay(organization_ids=(org.id,))
             mocked_auto_create.assert_not_called()
 
-    @patch('logging.Logger.exception')
+    @patch("logging.Logger.exception")
     def test_single_node_mesh(self, mocked_logger):
         devices, org = self._populate_mesh(SINGLE_NODE_MESH_DATA)
         self.assertEqual(Topology.objects.filter(organization=org).count(), 1)
         topology = Topology.objects.filter(organization=org).first()
         self.assertEqual(
-            WifiMesh.objects.filter(topology=topology, mesh_id='Test Mesh@11').count(),
+            WifiMesh.objects.filter(topology=topology, mesh_id="Test Mesh@11").count(),
             1,
         )
         self.assertEqual(
@@ -157,7 +157,7 @@ def test_single_node_mesh(self, mocked_logger):
     def test_mesh_id_changed(self):
         devices, org = self._populate_mesh(SIMPLE_MESH_DATA)
         self.assertEqual(Topology.objects.filter(organization=org).count(), 1)
-        self.assertEqual(WifiMesh.objects.filter(mesh_id='Test Mesh@11').count(), 1)
+        self.assertEqual(WifiMesh.objects.filter(mesh_id="Test Mesh@11").count(), 1)
         topology = Topology.objects.filter(organization=org).first()
         self.assertEqual(
             Node.objects.filter(
@@ -176,20 +176,20 @@ def test_mesh_id_changed(self):
         # Change mesh_id reported in the monitoring data
         mesh_data = deepcopy(SIMPLE_MESH_DATA)
         for device, interfaces in zip(devices, mesh_data.values()):
-            interfaces[0]['wireless']['ssid'] = 'New Mesh'
+            interfaces[0]["wireless"]["ssid"] = "New Mesh"
             response = self.client.post(
-                '{0}?key={1}&time={2}'.format(
-                    reverse('monitoring:api_device_metric', args=[device.id]),
+                "{0}?key={1}&time={2}".format(
+                    reverse("monitoring:api_device_metric", args=[device.id]),
                     device.key,
-                    now().utcnow().strftime('%d-%m-%Y_%H:%M:%S.%f'),
+                    now().utcnow().strftime("%d-%m-%Y_%H:%M:%S.%f"),
                 ),
                 data=json.dumps(
                     {
-                        'type': 'DeviceMonitoring',
-                        'interfaces': interfaces,
+                        "type": "DeviceMonitoring",
+                        "interfaces": interfaces,
                     }
                 ),
-                content_type='application/json',
+                content_type="application/json",
             )
             self.assertEqual(response.status_code, 200)
         create_mesh_topology.delay(organization_ids=(org.id,))
@@ -197,9 +197,9 @@ def test_mesh_id_changed(self):
         self.assertEqual(WifiMesh.objects.count(), 2)
         self.assertEqual(Node.objects.count(), 6)
         self.assertEqual(Link.objects.count(), 6)
-        self.assertEqual(WifiMesh.objects.filter(mesh_id='New Mesh@11').count(), 1)
+        self.assertEqual(WifiMesh.objects.filter(mesh_id="New Mesh@11").count(), 1)
         topology = Topology.objects.filter(
-            organization=org, wifimesh__mesh_id='New Mesh@11'
+            organization=org, wifimesh__mesh_id="New Mesh@11"
         ).first()
         self.assertEqual(
             Node.objects.filter(
@@ -223,36 +223,36 @@ def test_discard_old_monitoring_data(self):
         self.assertEqual(Topology.objects.count(), 1)
         topology = Topology.objects.first()
         self.assertEqual(topology.node_set.count(), 3)
-        self.assertEqual(topology.link_set.filter(status='up').count(), 3)
+        self.assertEqual(topology.link_set.filter(status="up").count(), 3)
 
         with freeze_time(now_time - timedelta(minutes=10)):
             # Only two devices sent monitoring data
             for device in devices[:2]:
                 response = self.client.post(
-                    '{0}?key={1}&time={2}'.format(
-                        reverse('monitoring:api_device_metric', args=[device.id]),
+                    "{0}?key={1}&time={2}".format(
+                        reverse("monitoring:api_device_metric", args=[device.id]),
                         device.key,
-                        now().utcnow().strftime('%d-%m-%Y_%H:%M:%S.%f'),
+                        now().utcnow().strftime("%d-%m-%Y_%H:%M:%S.%f"),
                     ),
                     data=json.dumps(
                         {
-                            'type': 'DeviceMonitoring',
-                            'interfaces': SIMPLE_MESH_DATA[device.mac_address],
+                            "type": "DeviceMonitoring",
+                            "interfaces": SIMPLE_MESH_DATA[device.mac_address],
                         }
                     ),
-                    content_type='application/json',
+                    content_type="application/json",
                 )
                 self.assertEqual(response.status_code, 200)
             create_mesh_topology.delay(organization_ids=(org.id,))
         self.assertEqual(Topology.objects.count(), 1)
         self.assertEqual(topology.node_set.count(), 3)
-        self.assertEqual(topology.link_set.filter(status='up').count(), 1)
+        self.assertEqual(topology.link_set.filter(status="up").count(), 1)
 
         # No device is sending monitoring data
         create_mesh_topology.delay(organization_ids=(org.id,))
         self.assertEqual(Topology.objects.count(), 1)
         self.assertEqual(topology.node_set.count(), 3)
-        self.assertEqual(topology.link_set.filter(status='up').count(), 0)
+        self.assertEqual(topology.link_set.filter(status="up").count(), 0)
 
     def test_topology_admin(self):
         """
@@ -267,13 +267,13 @@ def test_topology_admin(self):
         admin = self._create_admin()
         self.client.force_login(admin)
 
-        with self.subTest('Test add form'):
-            response = self.client.get(reverse(f'{self.prefix}_topology_add'))
-            self.assertContains(response, 'Wifi mesh')
+        with self.subTest("Test add form"):
+            response = self.client.get(reverse(f"{self.prefix}_topology_add"))
+            self.assertContains(response, "Wifi mesh")
 
-        with self.subTest('Test change form'):
+        with self.subTest("Test change form"):
             topology = self._create_topology()
             response = self.client.get(
-                reverse(f'{self.prefix}_topology_change', args=[topology.id])
+                reverse(f"{self.prefix}_topology_change", args=[topology.id])
             )
-            self.assertContains(response, 'Wifi mesh')
+            self.assertContains(response, "Wifi mesh")
diff --git a/openwisp_network_topology/integrations/device/tests/utils.py b/openwisp_network_topology/integrations/device/tests/utils.py
index f3b19fc5..a5625a69 100644
--- a/openwisp_network_topology/integrations/device/tests/utils.py
+++ b/openwisp_network_topology/integrations/device/tests/utils.py
@@ -9,9 +9,9 @@
 from openwisp_network_topology.tests.utils import CreateGraphObjectsMixin
 from openwisp_users.tests.utils import TestOrganizationMixin
 
-Node = swapper.load_model('topology', 'Node')
+Node = swapper.load_model("topology", "Node")
 
-Topology = swapper.load_model('topology', 'Topology')
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TopologyTestMixin(
@@ -29,18 +29,18 @@ def _init_test_node(
         self,
         topology,
         addresses=None,
-        label='test',
+        label="test",
         common_name=None,
         create=True,
     ):
         if not addresses:
-            addresses = ['netjson_id']
+            addresses = ["netjson_id"]
         node = Node(
             organization=topology.organization,
             topology=topology,
             label=label,
             addresses=addresses,
-            properties={'common_name': common_name},
+            properties={"common_name": common_name},
         )
         if create:
             node.full_clean()
@@ -49,22 +49,22 @@ def _init_test_node(
 
     def _init_wireguard_test_node(self, topology, addresses=[], create=True, **kwargs):
         if not addresses:
-            addresses = ['public_key']
+            addresses = ["public_key"]
         properties = {
-            'preshared_key': None,
-            'endpoint': None,
-            'latest_handsake': '0',
-            'transfer_rx': '0',
-            'transfer_tx': '0',
-            'persistent_keepalive': 'off',
-            'allowed_ips': ['10.0.0.2/32'],
+            "preshared_key": None,
+            "endpoint": None,
+            "latest_handsake": "0",
+            "transfer_rx": "0",
+            "transfer_tx": "0",
+            "persistent_keepalive": "off",
+            "allowed_ips": ["10.0.0.2/32"],
         }
         properties.update(kwargs)
-        allowed_ips = properties.get('allowed_ips')
+        allowed_ips = properties.get("allowed_ips")
         node = Node(
             organization=topology.organization,
             topology=topology,
-            label=','.join(allowed_ips),
+            label=",".join(allowed_ips),
             addresses=addresses,
             properties=properties,
         )
@@ -82,19 +82,19 @@ def _create_wireguard_test_env(self, parser):
 
     def _create_test_env(self, parser):
         organization = self._get_org()
-        vpn = self._create_vpn(name='test VPN', organization=organization)
+        vpn = self._create_vpn(name="test VPN", organization=organization)
         self._create_template(
-            name='VPN',
-            type='vpn',
+            name="VPN",
+            type="vpn",
             vpn=vpn,
             config=vpn.auto_client(),
             default=True,
             organization=organization,
         )
-        vpn2 = self._create_vpn(name='test VPN2', ca=vpn.ca, organization=organization)
+        vpn2 = self._create_vpn(name="test VPN2", ca=vpn.ca, organization=organization)
         self._create_template(
-            name='VPN2',
-            type='vpn',
+            name="VPN2",
+            type="vpn",
             vpn=vpn2,
             config=vpn.auto_client(),
             default=True,
diff --git a/openwisp_network_topology/management/commands/__init__.py b/openwisp_network_topology/management/commands/__init__.py
index 19654db5..2005bbd5 100644
--- a/openwisp_network_topology/management/commands/__init__.py
+++ b/openwisp_network_topology/management/commands/__init__.py
@@ -1,36 +1,36 @@
 import swapper
 from django.core.management.base import BaseCommand
 
-Topology = swapper.load_model('topology', 'Topology')
+Topology = swapper.load_model("topology", "Topology")
 
 
 class BaseUpdateCommand(BaseCommand):
-    help = 'Update network topology'
+    help = "Update network topology"
     topology_model = Topology
 
     def add_arguments(self, parser):
         parser.add_argument(
-            '--label',
-            action='store',
+            "--label",
+            action="store",
             default=None,
-            help='Will update topologies containing label',
+            help="Will update topologies containing label",
         )
 
     def handle(self, *args, **options):
-        self.topology_model.update_all(options['label'])
+        self.topology_model.update_all(options["label"])
 
 
 class BaseSaveSnapshotCommand(BaseCommand):
-    help = 'Save network topology graph snapshot'
+    help = "Save network topology graph snapshot"
     topology_model = Topology
 
     def add_arguments(self, parser):
         parser.add_argument(
-            '--label',
-            action='store',
+            "--label",
+            action="store",
             default=None,
-            help='Will save snapshots of topologies containing label',
+            help="Will save snapshots of topologies containing label",
         )
 
     def handle(self, *args, **options):
-        self.topology_model.save_snapshot_all(options['label'])
+        self.topology_model.save_snapshot_all(options["label"])
diff --git a/openwisp_network_topology/management/commands/upgrade_from_django_netjsongraph.py b/openwisp_network_topology/management/commands/upgrade_from_django_netjsongraph.py
index ed6b1654..5fad055d 100644
--- a/openwisp_network_topology/management/commands/upgrade_from_django_netjsongraph.py
+++ b/openwisp_network_topology/management/commands/upgrade_from_django_netjsongraph.py
@@ -9,29 +9,29 @@
 from swapper import get_model_name, load_model, split
 
 User = get_user_model()
-Topology = load_model('topology', 'Topology')
-Organization = load_model('openwisp_users', 'Organization')
+Topology = load_model("topology", "Topology")
+Organization = load_model("openwisp_users", "Organization")
 
 
 class BaseUpdateFromDjangoNetjsonGraph(BaseCommand):
-    help = 'Upgrade from django-netjsongraph'
-    app_label_users = split(get_model_name('openwisp_users', 'Organization'))[0]
-    app_label = split(get_model_name('topology', 'Topology'))[0]
+    help = "Upgrade from django-netjsongraph"
+    app_label_users = split(get_model_name("openwisp_users", "Organization"))[0]
+    app_label = split(get_model_name("topology", "Topology"))[0]
 
     def add_arguments(self, parser):
         parser.add_argument(
-            '--backup',
-            action='store',
+            "--backup",
+            action="store",
             default=settings.BASE_DIR,
-            help='(Optional) Path to the backup files',
+            help="(Optional) Path to the backup files",
         )
         parser.add_argument(
-            '--organization',
-            action='store',
+            "--organization",
+            action="store",
             default=None,
             help=(
-                '(Optional) organization UUID of the organization in '
-                'which you want to import the data.'
+                "(Optional) organization UUID of the organization in "
+                "which you want to import the data."
             ),
         )
 
@@ -44,22 +44,22 @@ def _get_updated_permission_list(
         permit_list = []
         for permit_pk in permissions_list:
             for item in permission_data:
-                if item['pk'] == permit_pk:
+                if item["pk"] == permit_pk:
                     for content in contenttype_data:
-                        if item['fields']['content_type'] == content['pk']:
-                            permit_app_label = content['fields']['app_label']
-                            if permit_app_label == 'django_netjsongraph':
+                        if item["fields"]["content_type"] == content["pk"]:
+                            permit_app_label = content["fields"]["app_label"]
+                            if permit_app_label == "django_netjsongraph":
                                 permit_app_label = self.app_label
                             elif (
-                                content['fields']['model'] in ['user', 'group']
-                                and permit_app_label == 'auth'
+                                content["fields"]["model"] in ["user", "group"]
+                                and permit_app_label == "auth"
                             ):
                                 permit_app_label = self.app_label_users
                     try:
                         permit_list.append(
                             Permission.objects.get(
                                 content_type__app_label=permit_app_label,
-                                codename=item['fields']['codename'],
+                                codename=item["fields"]["codename"],
                             ).pk
                         )
                     except Permission.DoesNotExist:  # pragma: nocover
@@ -67,8 +67,8 @@ def _get_updated_permission_list(
         return permit_list
 
     def handle(self, *args, **options):
-        if options['organization']:
-            org = Organization.objects.get(pk=options['organization'])
+        if options["organization"]:
+            org = Organization.objects.get(pk=options["organization"])
         else:
             org = Organization.objects.first()
 
@@ -77,14 +77,14 @@ def handle(self, *args, **options):
             netjsongraph_data = json.load(netjsongraph)
         # Make changes
         for data in netjsongraph_data:
-            data['fields']['organization'] = str(org.pk)
-            data['model'] = f'{self.app_label}.{data["model"].split(".")[1]}'
+            data["fields"]["organization"] = str(org.pk)
+            data["model"] = f'{self.app_label}.{data["model"].split(".")[1]}'
         # Save in anotherfile
-        with open(f'{options["backup"]}/netjsongraph_loaded.json', 'w') as outfile:
+        with open(f'{options["backup"]}/netjsongraph_loaded.json', "w") as outfile:
             json.dump(netjsongraph_data, outfile)
         # Load to database
         call_command(
-            'loaddata', f'{options["backup"]}/netjsongraph_loaded.json', verbosity=0
+            "loaddata", f'{options["backup"]}/netjsongraph_loaded.json', verbosity=0
         )
 
         # Group Model
@@ -96,16 +96,16 @@ def handle(self, *args, **options):
             group_data = json.load(group)
         load_group_data = []
         for data in group_data:
-            if not Group.objects.filter(name=data['fields']['name']).exists():
+            if not Group.objects.filter(name=data["fields"]["name"]).exists():
                 load_group_data.append(
                     {
-                        'model': f'{self.app_label_users}.group',
-                        'pk': data['pk'] + Group.objects.count(),
-                        'fields': {
-                            'name': data['fields']['name'],
-                            'permissions': self._get_updated_permission_list(
+                        "model": f"{self.app_label_users}.group",
+                        "pk": data["pk"] + Group.objects.count(),
+                        "fields": {
+                            "name": data["fields"]["name"],
+                            "permissions": self._get_updated_permission_list(
                                 permission_data,
-                                data['fields']['permissions'],
+                                data["fields"]["permissions"],
                                 contenttype_data,
                             ),
                         },
@@ -113,11 +113,11 @@ def handle(self, *args, **options):
                 )
         if load_group_data:
             # Save in anotherfile
-            with open(f'{options["backup"]}/group_loaded.json', 'w') as outfile:
+            with open(f'{options["backup"]}/group_loaded.json', "w") as outfile:
                 json.dump(load_group_data, outfile)
             # Load to database
             call_command(
-                'loaddata', f'{options["backup"]}/group_loaded.json', verbosity=0
+                "loaddata", f'{options["backup"]}/group_loaded.json', verbosity=0
             )
 
         # User Model
@@ -127,51 +127,51 @@ def handle(self, *args, **options):
         org_users_data = []
         load_users_data = []
         for data in users_data:
-            data['model'] = f'{self.app_label_users}.user'
-            data['pk'] = self.int_to_uuid(data['pk'])
+            data["model"] = f"{self.app_label_users}.user"
+            data["pk"] = self.int_to_uuid(data["pk"])
             # If the user doesn't have an email, give them a
             # @example.com email but in openwisp-network-topology
             # email is UNIQUE.
-            if not data['fields']['email']:
-                data['fields']['email'] = f'{data["fields"]["username"]}@example.com'
+            if not data["fields"]["email"]:
+                data["fields"]["email"] = f'{data["fields"]["username"]}@example.com'
             group_list = []
-            for group_pk in data['fields']['groups']:
+            for group_pk in data["fields"]["groups"]:
                 for item in group_data:
-                    if item['pk'] == group_pk:
+                    if item["pk"] == group_pk:
                         group_list.append(
-                            Group.objects.filter(name=item['fields']['name']).first().pk
+                            Group.objects.filter(name=item["fields"]["name"]).first().pk
                         )
-            data['fields']['groups'] = group_list
-            data['fields']['user_permissions'] = self._get_updated_permission_list(
-                permission_data, data['fields']['user_permissions'], contenttype_data
+            data["fields"]["groups"] = group_list
+            data["fields"]["user_permissions"] = self._get_updated_permission_list(
+                permission_data, data["fields"]["user_permissions"], contenttype_data
             )
-            if not User.objects.filter(email=data['fields']['email']):
+            if not User.objects.filter(email=data["fields"]["email"]):
                 load_users_data.append(data)
-                if not data['fields']['is_superuser']:
+                if not data["fields"]["is_superuser"]:
                     org_users_data.append(
                         {
-                            'model': f'{self.app_label_users}.organizationuser',
-                            'pk': str(uuid.uuid4()),
-                            'fields': {
-                                'created': data['fields']['date_joined'],
-                                'modified': data['fields']['date_joined'],
-                                'is_admin': False,
-                                'user': data['pk'],
-                                'organization': str(org.pk),
+                            "model": f"{self.app_label_users}.organizationuser",
+                            "pk": str(uuid.uuid4()),
+                            "fields": {
+                                "created": data["fields"]["date_joined"],
+                                "modified": data["fields"]["date_joined"],
+                                "is_admin": False,
+                                "user": data["pk"],
+                                "organization": str(org.pk),
                             },
                         }
                     )
         load_users_data.extend(org_users_data)
         if load_users_data:
             # Save in anotherfile
-            with open(f'{options["backup"]}/user_loaded.json', 'w') as outfile:
+            with open(f'{options["backup"]}/user_loaded.json', "w") as outfile:
                 json.dump(load_users_data, outfile)
             # Load to database
             call_command(
-                'loaddata', f'{options["backup"]}/user_loaded.json', verbosity=0
+                "loaddata", f'{options["backup"]}/user_loaded.json', verbosity=0
             )
 
-        self.stdout.write(self.style.SUCCESS('Migration Process Complete!'))
+        self.stdout.write(self.style.SUCCESS("Migration Process Complete!"))
 
 
 class Command(BaseUpdateFromDjangoNetjsonGraph):
diff --git a/openwisp_network_topology/migrations/0001_initial.py b/openwisp_network_topology/migrations/0001_initial.py
index 690c64a5..77e23ea5 100644
--- a/openwisp_network_topology/migrations/0001_initial.py
+++ b/openwisp_network_topology/migrations/0001_initial.py
@@ -21,15 +21,15 @@ class Migration(migrations.Migration):
     initial = True
 
     dependencies = [
-        dependency(*split(settings.AUTH_USER_MODEL), version='0004_default_groups'),
+        dependency(*split(settings.AUTH_USER_MODEL), version="0004_default_groups"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='Link',
+            name="Link",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -38,57 +38,57 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('cost', models.FloatField()),
-                ('cost_text', models.CharField(blank=True, max_length=24)),
+                ("cost", models.FloatField()),
+                ("cost_text", models.CharField(blank=True, max_length=24)),
                 (
-                    'status',
+                    "status",
                     model_utils.fields.StatusField(
-                        choices=[('up', 'up'), ('down', 'down')],
-                        default='up',
+                        choices=[("up", "up"), ("down", "down")],
+                        default="up",
                         max_length=100,
                         no_check_for_status=True,
                     ),
                 ),
                 (
-                    'properties',
+                    "properties",
                     jsonfield.fields.JSONField(
                         blank=True,
                         default=dict,
-                        dump_kwargs={'indent': 4},
-                        load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                        dump_kwargs={"indent": 4},
+                        load_kwargs={"object_pairs_hook": collections.OrderedDict},
                     ),
                 ),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
             ],
-            options={'abstract': False},
+            options={"abstract": False},
         ),
         migrations.CreateModel(
-            name='Node',
+            name="Node",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -97,48 +97,48 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('label', models.CharField(blank=True, max_length=64)),
-                ('addresses', models.CharField(db_index=True, max_length=510)),
+                ("label", models.CharField(blank=True, max_length=64)),
+                ("addresses", models.CharField(db_index=True, max_length=510)),
                 (
-                    'properties',
+                    "properties",
                     jsonfield.fields.JSONField(
                         blank=True,
                         default=dict,
-                        dump_kwargs={'indent': 4},
-                        load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                        dump_kwargs={"indent": 4},
+                        load_kwargs={"object_pairs_hook": collections.OrderedDict},
                     ),
                 ),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
             ],
-            options={'abstract': False},
+            options={"abstract": False},
         ),
         migrations.CreateModel(
-            name='Topology',
+            name="Topology",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -147,157 +147,157 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('label', models.CharField(max_length=64, verbose_name='label')),
+                ("label", models.CharField(max_length=64, verbose_name="label")),
                 (
-                    'parser',
+                    "parser",
                     models.CharField(
                         choices=[
-                            ('netdiff.OlsrParser', 'OLSRd (txtinfo/jsoninfo)'),
+                            ("netdiff.OlsrParser", "OLSRd (txtinfo/jsoninfo)"),
                             (
-                                'netdiff.BatmanParser',
-                                'batman-advanced (jsondoc/txtinfo)',
+                                "netdiff.BatmanParser",
+                                "batman-advanced (jsondoc/txtinfo)",
                             ),
-                            ('netdiff.BmxParser', 'BMX6 (q6m)'),
-                            ('netdiff.NetJsonParser', 'NetJSON NetworkGraph'),
-                            ('netdiff.CnmlParser', 'CNML 1.0'),
+                            ("netdiff.BmxParser", "BMX6 (q6m)"),
+                            ("netdiff.NetJsonParser", "NetJSON NetworkGraph"),
+                            ("netdiff.CnmlParser", "CNML 1.0"),
                         ],
-                        help_text='Select topology format',
+                        help_text="Select topology format",
                         max_length=128,
-                        verbose_name='format',
+                        verbose_name="format",
                     ),
                 ),
                 (
-                    'strategy',
+                    "strategy",
                     models.CharField(
-                        choices=[('fetch', 'FETCH'), ('receive', 'RECEIVE')],
+                        choices=[("fetch", "FETCH"), ("receive", "RECEIVE")],
                         db_index=True,
-                        default='fetch',
+                        default="fetch",
                         max_length=16,
-                        verbose_name='strategy',
+                        verbose_name="strategy",
                     ),
                 ),
                 (
-                    'url',
+                    "url",
                     models.URLField(
                         blank=True,
-                        help_text='Topology data will be fetched from this URL (FETCH strategy)',
-                        verbose_name='url',
+                        help_text="Topology data will be fetched from this URL (FETCH strategy)",
+                        verbose_name="url",
                     ),
                 ),
                 (
-                    'key',
+                    "key",
                     openwisp_utils.base.KeyField(
                         blank=True,
                         default=openwisp_utils.utils.get_random_key,
-                        help_text='key needed to update topology from nodes ',
+                        help_text="key needed to update topology from nodes ",
                         max_length=64,
                         validators=[
                             django.core.validators.RegexValidator(
-                                re.compile('^[^\\s/\\.]+$'),
-                                code='invalid',
-                                message='This value must not contain spaces, dots or slashes.',
+                                re.compile("^[^\\s/\\.]+$"),
+                                code="invalid",
+                                message="This value must not contain spaces, dots or slashes.",
                             )
                         ],
-                        verbose_name='key',
+                        verbose_name="key",
                     ),
                 ),
                 (
-                    'expiration_time',
+                    "expiration_time",
                     models.PositiveIntegerField(
                         default=0,
                         help_text=(
                             '"Expiration Time" in seconds: setting this to 0 will '
-                            'immediately mark missing links as down; a value higher '
-                            'than 0 will delay marking missing links as down until '
+                            "immediately mark missing links as down; a value higher "
+                            "than 0 will delay marking missing links as down until "
                             'the "modified" field of a link is older than "Expiration Time"'
                         ),
-                        verbose_name='expiration time',
+                        verbose_name="expiration time",
                     ),
                 ),
                 (
-                    'published',
+                    "published",
                     models.BooleanField(
                         default=True,
                         help_text="Unpublished topologies won't be updated or shown in the visualizer",
-                        verbose_name='published',
+                        verbose_name="published",
                     ),
                 ),
                 (
-                    'protocol',
+                    "protocol",
                     models.CharField(
-                        blank=True, max_length=64, verbose_name='protocol'
+                        blank=True, max_length=64, verbose_name="protocol"
                     ),
                 ),
                 (
-                    'version',
-                    models.CharField(blank=True, max_length=24, verbose_name='version'),
+                    "version",
+                    models.CharField(blank=True, max_length=24, verbose_name="version"),
                 ),
                 (
-                    'revision',
+                    "revision",
                     models.CharField(
-                        blank=True, max_length=64, verbose_name='revision'
+                        blank=True, max_length=64, verbose_name="revision"
                     ),
                 ),
                 (
-                    'metric',
-                    models.CharField(blank=True, max_length=24, verbose_name='metric'),
+                    "metric",
+                    models.CharField(blank=True, max_length=24, verbose_name="metric"),
                 ),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
             ],
-            options={'verbose_name_plural': 'topologies', 'abstract': False},
+            options={"verbose_name_plural": "topologies", "abstract": False},
         ),
         migrations.AddField(
-            model_name='node',
-            name='topology',
+            model_name="node",
+            name="topology",
             field=models.ForeignKey(
-                on_delete=django.db.models.deletion.CASCADE, to='topology.Topology'
+                on_delete=django.db.models.deletion.CASCADE, to="topology.Topology"
             ),
         ),
         migrations.AddField(
-            model_name='link',
-            name='source',
+            model_name="link",
+            name="source",
             field=models.ForeignKey(
                 on_delete=django.db.models.deletion.CASCADE,
-                related_name='source_link_set',
-                to='topology.Node',
+                related_name="source_link_set",
+                to="topology.Node",
             ),
         ),
         migrations.AddField(
-            model_name='link',
-            name='target',
+            model_name="link",
+            name="target",
             field=models.ForeignKey(
                 on_delete=django.db.models.deletion.CASCADE,
-                related_name='source_target_set',
-                to='topology.Node',
+                related_name="source_target_set",
+                to="topology.Node",
             ),
         ),
         migrations.AddField(
-            model_name='link',
-            name='topology',
+            model_name="link",
+            name="topology",
             field=models.ForeignKey(
-                on_delete=django.db.models.deletion.CASCADE, to='topology.Topology'
+                on_delete=django.db.models.deletion.CASCADE, to="topology.Topology"
             ),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0002_snapshot.py b/openwisp_network_topology/migrations/0002_snapshot.py
index 0a0aa189..74a592a9 100644
--- a/openwisp_network_topology/migrations/0002_snapshot.py
+++ b/openwisp_network_topology/migrations/0002_snapshot.py
@@ -11,14 +11,14 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0001_initial')]
+    dependencies = [("topology", "0001_initial")]
 
     operations = [
         migrations.CreateModel(
-            name='Snapshot',
+            name="Snapshot",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -27,39 +27,39 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('data', models.TextField()),
-                ('date', models.DateField(auto_now=True)),
+                ("data", models.TextField()),
+                ("date", models.DateField(auto_now=True)),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
                 (
-                    'topology',
+                    "topology",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to='topology.Topology',
+                        to="topology.Topology",
                     ),
                 ),
             ],
-            options={'abstract': False, 'verbose_name_plural': 'snapshots'},
+            options={"abstract": False, "verbose_name_plural": "snapshots"},
         )
     ]
diff --git a/openwisp_network_topology/migrations/0003_link_status_and_openvpn_parser.py b/openwisp_network_topology/migrations/0003_link_status_and_openvpn_parser.py
index 02178a0f..e2202268 100644
--- a/openwisp_network_topology/migrations/0003_link_status_and_openvpn_parser.py
+++ b/openwisp_network_topology/migrations/0003_link_status_and_openvpn_parser.py
@@ -4,29 +4,29 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0002_snapshot')]
+    dependencies = [("topology", "0002_snapshot")]
 
     operations = [
         migrations.AddField(
-            model_name='link',
-            name='status_changed',
+            model_name="link",
+            name="status_changed",
             field=models.DateTimeField(auto_now=True),
         ),
         migrations.AlterField(
-            model_name='topology',
-            name='parser',
+            model_name="topology",
+            name="parser",
             field=models.CharField(
                 choices=[
-                    ('netdiff.OlsrParser', 'OLSRd (txtinfo/jsoninfo)'),
-                    ('netdiff.BatmanParser', 'batman-advanced (jsondoc/txtinfo)'),
-                    ('netdiff.BmxParser', 'BMX6 (q6m)'),
-                    ('netdiff.NetJsonParser', 'NetJSON NetworkGraph'),
-                    ('netdiff.CnmlParser', 'CNML 1.0'),
-                    ('netdiff.OpenvpnParser', 'OpenVPN'),
+                    ("netdiff.OlsrParser", "OLSRd (txtinfo/jsoninfo)"),
+                    ("netdiff.BatmanParser", "batman-advanced (jsondoc/txtinfo)"),
+                    ("netdiff.BmxParser", "BMX6 (q6m)"),
+                    ("netdiff.NetJsonParser", "NetJSON NetworkGraph"),
+                    ("netdiff.CnmlParser", "CNML 1.0"),
+                    ("netdiff.OpenvpnParser", "OpenVPN"),
                 ],
-                help_text='Select topology format',
+                help_text="Select topology format",
                 max_length=128,
-                verbose_name='format',
+                verbose_name="format",
             ),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0004_fixed_target_link_set.py b/openwisp_network_topology/migrations/0004_fixed_target_link_set.py
index 6c922af9..48a179c8 100644
--- a/openwisp_network_topology/migrations/0004_fixed_target_link_set.py
+++ b/openwisp_network_topology/migrations/0004_fixed_target_link_set.py
@@ -5,16 +5,16 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0003_link_status_and_openvpn_parser')]
+    dependencies = [("topology", "0003_link_status_and_openvpn_parser")]
 
     operations = [
         migrations.AlterField(
-            model_name='link',
-            name='target',
+            model_name="link",
+            name="target",
             field=models.ForeignKey(
                 on_delete=django.db.models.deletion.CASCADE,
-                related_name='target_link_set',
-                to='topology.Node',
+                related_name="target_link_set",
+                to="topology.Node",
             ),
         )
     ]
diff --git a/openwisp_network_topology/migrations/0005_default_operator_permission.py b/openwisp_network_topology/migrations/0005_default_operator_permission.py
index a77aedaf..ed609134 100644
--- a/openwisp_network_topology/migrations/0005_default_operator_permission.py
+++ b/openwisp_network_topology/migrations/0005_default_operator_permission.py
@@ -14,23 +14,23 @@ def _add_permission_to_group(group, models, operations):
             for operation in operations:
                 try:
                     permission = Permission.objects.get(
-                        codename='{}_{}'.format(operation, model)
+                        codename="{}_{}".format(operation, model)
                     )
                 except Permission.DoesNotExist:
                     continue
                 else:
                     group.permissions.add(permission.pk)
 
-    operators_can_manage = ['link', 'node']
-    operators_can_only_view = ['topology']
-    admin_can_manage = ['link', 'node', 'topology']
-    manage_operations = ['add', 'change', 'delete', 'view']
-    view_only_operations = ['view']
-    Group = apps.get_model('openwisp_users', 'Group')
+    operators_can_manage = ["link", "node"]
+    operators_can_only_view = ["topology"]
+    admin_can_manage = ["link", "node", "topology"]
+    manage_operations = ["add", "change", "delete", "view"]
+    view_only_operations = ["view"]
+    Group = apps.get_model("openwisp_users", "Group")
 
     try:
-        admin = Group.objects.get(name='Administrator')
-        operator = Group.objects.get(name='Operator')
+        admin = Group.objects.get(name="Administrator")
+        operator = Group.objects.get(name="Operator")
     # consider failures custom cases
     # that do not have to be dealt with
     except Group.DoesNotExist:
@@ -45,8 +45,8 @@ def _add_permission_to_group(group, models, operations):
 
 class Migration(migrations.Migration):
     dependencies = [
-        dependency(*split(settings.AUTH_USER_MODEL), version='0004_default_groups'),
-        ('topology', '0004_fixed_target_link_set'),
+        dependency(*split(settings.AUTH_USER_MODEL), version="0004_default_groups"),
+        ("topology", "0004_fixed_target_link_set"),
     ]
     operations = [
         migrations.RunPython(
diff --git a/openwisp_network_topology/migrations/0006_reformat_addresses.py b/openwisp_network_topology/migrations/0006_reformat_addresses.py
index 42524ff1..820f16d5 100644
--- a/openwisp_network_topology/migrations/0006_reformat_addresses.py
+++ b/openwisp_network_topology/migrations/0006_reformat_addresses.py
@@ -2,23 +2,23 @@
 
 
 def reformat_address_forward(apps, schema_editor):
-    Node = apps.get_model('topology', 'Node')
+    Node = apps.get_model("topology", "Node")
     for node in Node.objects.all():
-        if not node.addresses.startswith(';'):
-            node.addresses = ';{0}'.format(node.addresses)
+        if not node.addresses.startswith(";"):
+            node.addresses = ";{0}".format(node.addresses)
             node.save()
 
 
 def reformat_address_backward(apps, schema_editor):
-    Fake_node_model = apps.get_model('topology', 'Node')
+    Fake_node_model = apps.get_model("topology", "Node")
     for node in Fake_node_model.objects.all():
-        if node.addresses.startswith(';'):
+        if node.addresses.startswith(";"):
             node.addresses = node.addresses[1:]
             node.save()
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0005_default_operator_permission')]
+    dependencies = [("topology", "0005_default_operator_permission")]
 
     operations = [
         migrations.RunPython(reformat_address_forward, reformat_address_backward)
diff --git a/openwisp_network_topology/migrations/0007_create_new_address_field.py b/openwisp_network_topology/migrations/0007_create_new_address_field.py
index d4a84664..25199af5 100644
--- a/openwisp_network_topology/migrations/0007_create_new_address_field.py
+++ b/openwisp_network_topology/migrations/0007_create_new_address_field.py
@@ -5,15 +5,15 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0006_reformat_addresses')]
+    dependencies = [("topology", "0006_reformat_addresses")]
 
     operations = [
         migrations.RenameField(
-            model_name='node', old_name='addresses', new_name='addresses_old'
+            model_name="node", old_name="addresses", new_name="addresses_old"
         ),
         migrations.AddField(
-            model_name='node',
-            name='addresses',
+            model_name="node",
+            name="addresses",
             field=jsonfield.fields.JSONField(default=[]),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0008_migrate_addresses_data.py b/openwisp_network_topology/migrations/0008_migrate_addresses_data.py
index 2ecdc962..55fa06c7 100644
--- a/openwisp_network_topology/migrations/0008_migrate_addresses_data.py
+++ b/openwisp_network_topology/migrations/0008_migrate_addresses_data.py
@@ -6,7 +6,7 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0007_create_new_address_field')]
+    dependencies = [("topology", "0007_create_new_address_field")]
 
     operations = [
         migrations.RunPython(migrate_addresses, reverse_code=migrations.RunPython.noop)
diff --git a/openwisp_network_topology/migrations/0009_remove_old_addresses.py b/openwisp_network_topology/migrations/0009_remove_old_addresses.py
index 24c95019..a39bd302 100644
--- a/openwisp_network_topology/migrations/0009_remove_old_addresses.py
+++ b/openwisp_network_topology/migrations/0009_remove_old_addresses.py
@@ -4,6 +4,6 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0008_migrate_addresses_data')]
+    dependencies = [("topology", "0008_migrate_addresses_data")]
 
-    operations = [migrations.RemoveField(model_name='node', name='addresses_old')]
+    operations = [migrations.RemoveField(model_name="node", name="addresses_old")]
diff --git a/openwisp_network_topology/migrations/0010_properties_json.py b/openwisp_network_topology/migrations/0010_properties_json.py
index 7be7f396..02495a00 100644
--- a/openwisp_network_topology/migrations/0010_properties_json.py
+++ b/openwisp_network_topology/migrations/0010_properties_json.py
@@ -8,38 +8,38 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0009_remove_old_addresses')]
+    dependencies = [("topology", "0009_remove_old_addresses")]
 
     operations = [
         migrations.AlterField(
-            model_name='link',
-            name='properties',
+            model_name="link",
+            name="properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
             ),
         ),
         migrations.AlterField(
-            model_name='node',
-            name='addresses',
+            model_name="node",
+            name="addresses",
             field=jsonfield.fields.JSONField(blank=True, default=[]),
         ),
         migrations.AlterField(
-            model_name='node',
-            name='properties',
+            model_name="node",
+            name="properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
             ),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0011_fix_link_properties.py b/openwisp_network_topology/migrations/0011_fix_link_properties.py
index 30062565..9f7be14b 100644
--- a/openwisp_network_topology/migrations/0011_fix_link_properties.py
+++ b/openwisp_network_topology/migrations/0011_fix_link_properties.py
@@ -4,7 +4,7 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0010_properties_json')]
+    dependencies = [("topology", "0010_properties_json")]
 
     operations = [
         migrations.RunPython(
diff --git a/openwisp_network_topology/migrations/0012_update_openvpn_netjson_ids.py b/openwisp_network_topology/migrations/0012_update_openvpn_netjson_ids.py
index 55df3f8e..dc8b55f0 100644
--- a/openwisp_network_topology/migrations/0012_update_openvpn_netjson_ids.py
+++ b/openwisp_network_topology/migrations/0012_update_openvpn_netjson_ids.py
@@ -4,7 +4,7 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0011_fix_link_properties')]
+    dependencies = [("topology", "0011_fix_link_properties")]
 
     operations = [
         migrations.RunPython(
diff --git a/openwisp_network_topology/migrations/0013_add_user_defined_properties_field.py b/openwisp_network_topology/migrations/0013_add_user_defined_properties_field.py
index 8d95520a..6a94627e 100644
--- a/openwisp_network_topology/migrations/0013_add_user_defined_properties_field.py
+++ b/openwisp_network_topology/migrations/0013_add_user_defined_properties_field.py
@@ -8,37 +8,37 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('topology', '0012_update_openvpn_netjson_ids')]
+    dependencies = [("topology", "0012_update_openvpn_netjson_ids")]
 
     operations = [
         migrations.AddField(
-            model_name='link',
-            name='user_properties',
+            model_name="link",
+            name="user_properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                help_text='If you need to add additional data to this link use this field',
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
-                verbose_name='user defined properties',
+                help_text="If you need to add additional data to this link use this field",
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
+                verbose_name="user defined properties",
             ),
         ),
         migrations.AddField(
-            model_name='node',
-            name='user_properties',
+            model_name="node",
+            name="user_properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                help_text='If you need to add additional data to this node use this field',
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
-                verbose_name='user defined properties',
+                help_text="If you need to add additional data to this node use this field",
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
+                verbose_name="user defined properties",
             ),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0014_remove_snapshot_organization.py b/openwisp_network_topology/migrations/0014_remove_snapshot_organization.py
index 98757935..c4616dfb 100644
--- a/openwisp_network_topology/migrations/0014_remove_snapshot_organization.py
+++ b/openwisp_network_topology/migrations/0014_remove_snapshot_organization.py
@@ -5,12 +5,12 @@
 
 class Migration(migrations.Migration):
     dependencies = [
-        ('topology', '0013_add_user_defined_properties_field'),
+        ("topology", "0013_add_user_defined_properties_field"),
     ]
 
     operations = [
         migrations.RemoveField(
-            model_name='snapshot',
-            name='organization',
+            model_name="snapshot",
+            name="organization",
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0015_shareable_topology_node_link.py b/openwisp_network_topology/migrations/0015_shareable_topology_node_link.py
index 1d4cee90..5b6a8dcf 100644
--- a/openwisp_network_topology/migrations/0015_shareable_topology_node_link.py
+++ b/openwisp_network_topology/migrations/0015_shareable_topology_node_link.py
@@ -7,41 +7,41 @@
 
 class Migration(migrations.Migration):
     dependencies = [
-        ('topology', '0014_remove_snapshot_organization'),
+        ("topology", "0014_remove_snapshot_organization"),
     ]
 
     operations = [
         migrations.AlterField(
-            model_name='link',
-            name='organization',
+            model_name="link",
+            name="organization",
             field=models.ForeignKey(
                 blank=True,
                 null=True,
                 on_delete=django.db.models.deletion.CASCADE,
-                to=get_model_name('openwisp_users', 'Organization'),
-                verbose_name='organization',
+                to=get_model_name("openwisp_users", "Organization"),
+                verbose_name="organization",
             ),
         ),
         migrations.AlterField(
-            model_name='node',
-            name='organization',
+            model_name="node",
+            name="organization",
             field=models.ForeignKey(
                 blank=True,
                 null=True,
                 on_delete=django.db.models.deletion.CASCADE,
-                to=get_model_name('openwisp_users', 'Organization'),
-                verbose_name='organization',
+                to=get_model_name("openwisp_users", "Organization"),
+                verbose_name="organization",
             ),
         ),
         migrations.AlterField(
-            model_name='topology',
-            name='organization',
+            model_name="topology",
+            name="organization",
             field=models.ForeignKey(
                 blank=True,
                 null=True,
                 on_delete=django.db.models.deletion.CASCADE,
-                to=get_model_name('openwisp_users', 'Organization'),
-                verbose_name='organization',
+                to=get_model_name("openwisp_users", "Organization"),
+                verbose_name="organization",
             ),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/0016_alter_topology_parser.py b/openwisp_network_topology/migrations/0016_alter_topology_parser.py
index b8b26eb2..65cc6840 100644
--- a/openwisp_network_topology/migrations/0016_alter_topology_parser.py
+++ b/openwisp_network_topology/migrations/0016_alter_topology_parser.py
@@ -5,27 +5,27 @@
 
 class Migration(migrations.Migration):
     dependencies = [
-        ('topology', '0015_shareable_topology_node_link'),
+        ("topology", "0015_shareable_topology_node_link"),
     ]
 
     operations = [
         migrations.AlterField(
-            model_name='topology',
-            name='parser',
+            model_name="topology",
+            name="parser",
             field=models.CharField(
                 choices=[
-                    ('netdiff.OlsrParser', 'OLSRd (txtinfo/jsoninfo)'),
-                    ('netdiff.BatmanParser', 'batman-advanced (jsondoc/txtinfo)'),
-                    ('netdiff.BmxParser', 'BMX6 (q6m)'),
-                    ('netdiff.NetJsonParser', 'NetJSON NetworkGraph'),
-                    ('netdiff.CnmlParser', 'CNML 1.0'),
-                    ('netdiff.OpenvpnParser', 'OpenVPN'),
-                    ('netdiff.WireguardParser', 'Wireguard'),
-                    ('netdiff.ZeroTierParser', 'ZeroTier'),
+                    ("netdiff.OlsrParser", "OLSRd (txtinfo/jsoninfo)"),
+                    ("netdiff.BatmanParser", "batman-advanced (jsondoc/txtinfo)"),
+                    ("netdiff.BmxParser", "BMX6 (q6m)"),
+                    ("netdiff.NetJsonParser", "NetJSON NetworkGraph"),
+                    ("netdiff.CnmlParser", "CNML 1.0"),
+                    ("netdiff.OpenvpnParser", "OpenVPN"),
+                    ("netdiff.WireguardParser", "Wireguard"),
+                    ("netdiff.ZeroTierParser", "ZeroTier"),
                 ],
-                help_text='Select topology format',
+                help_text="Select topology format",
                 max_length=128,
-                verbose_name='format',
+                verbose_name="format",
             ),
         ),
     ]
diff --git a/openwisp_network_topology/migrations/__init__.py b/openwisp_network_topology/migrations/__init__.py
index 8d646a7f..b5ffba00 100644
--- a/openwisp_network_topology/migrations/__init__.py
+++ b/openwisp_network_topology/migrations/__init__.py
@@ -10,19 +10,19 @@ def get_model(apps, app_name, model):
 
 
 def migrate_addresses(apps, schema_editor):
-    Node = get_model(apps, 'topology', 'Node')
+    Node = get_model(apps, "topology", "Node")
     for node in Node.objects.iterator():
-        addresses = node.addresses_old.replace(' ', '')
-        if addresses.startswith(';'):
+        addresses = node.addresses_old.replace(" ", "")
+        if addresses.startswith(";"):
             addresses = addresses[1:]
-        addresses = addresses[0:-1].split(';')
+        addresses = addresses[0:-1].split(";")
         node.addresses = addresses
         node.save()
 
 
 def migrate_openvpn_ids_0012(apps, schema_editor):
-    Node = get_model(apps, 'topology', 'Node')
-    queryset = Node.objects.filter(topology__parser='netdiff.OpenvpnParser')
+    Node = get_model(apps, "topology", "Node")
+    queryset = Node.objects.filter(topology__parser="netdiff.OpenvpnParser")
     for node in queryset.iterator():
         node.addresses[0] = node.label
         node.full_clean()
@@ -30,7 +30,7 @@ def migrate_openvpn_ids_0012(apps, schema_editor):
 
 
 def fix_link_properties(apps, schema_editor):
-    Link = get_model(apps, 'topology', 'Link')
+    Link = get_model(apps, "topology", "Link")
     for link in Link.objects.all():
         link.full_clean()
         link.save()
diff --git a/openwisp_network_topology/models.py b/openwisp_network_topology/models.py
index 35c40fab..41b6dc44 100644
--- a/openwisp_network_topology/models.py
+++ b/openwisp_network_topology/models.py
@@ -9,22 +9,22 @@
 class Link(AbstractLink):
     class Meta(AbstractLink.Meta):
         abstract = False
-        swappable = swapper.swappable_setting('topology', 'Link')
+        swappable = swapper.swappable_setting("topology", "Link")
 
 
 class Node(AbstractNode):
     class Meta(AbstractNode.Meta):
         abstract = False
-        swappable = swapper.swappable_setting('topology', 'Node')
+        swappable = swapper.swappable_setting("topology", "Node")
 
 
 class Snapshot(AbstractSnapshot):
     class Meta(AbstractSnapshot.Meta):
         abstract = False
-        swappable = swapper.swappable_setting('topology', 'Snapshot')
+        swappable = swapper.swappable_setting("topology", "Snapshot")
 
 
 class Topology(AbstractTopology):
     class Meta(AbstractTopology.Meta):
         abstract = False
-        swappable = swapper.swappable_setting('topology', 'Topology')
+        swappable = swapper.swappable_setting("topology", "Topology")
diff --git a/openwisp_network_topology/routing.py b/openwisp_network_topology/routing.py
index 2ea0c44d..da5dae16 100644
--- a/openwisp_network_topology/routing.py
+++ b/openwisp_network_topology/routing.py
@@ -6,7 +6,7 @@
     # This route is used by both
     # the admin and non-admin topology view
     path(
-        'ws/network-topology/topology/<uuid:pk>/',
+        "ws/network-topology/topology/<uuid:pk>/",
         consumers.TopologyConsumer.as_asgi(),
     ),
 ]
diff --git a/openwisp_network_topology/settings.py b/openwisp_network_topology/settings.py
index 4b423d4d..5697d618 100644
--- a/openwisp_network_topology/settings.py
+++ b/openwisp_network_topology/settings.py
@@ -5,41 +5,41 @@
 # 'pre_django_setup' is supposed to be a logger
 # that can work before registered Apps are
 # ready in django.setup() process.
-logger = logging.getLogger('pre_django_setup')
+logger = logging.getLogger("pre_django_setup")
 
 
 def get_settings_value(option, default):
     outdated_option_used = False
-    if hasattr(settings, f'NETJSONGRAPH_{option}'):
-        outdated_option_used = 'NETJSONGRAPH'
-    elif hasattr(settings, f'TOPOLOGY_{option}'):
-        outdated_option_used = 'TOPOLOGY'
+    if hasattr(settings, f"NETJSONGRAPH_{option}"):
+        outdated_option_used = "NETJSONGRAPH"
+    elif hasattr(settings, f"TOPOLOGY_{option}"):
+        outdated_option_used = "TOPOLOGY"
     if outdated_option_used:
         logger.warn(
-            f'{outdated_option_used}_{option} setting is deprecated. It will be removed '
-            f'in the future, please use OPENWISP_NETWORK_TOPOLOGY_{option} instead.'
+            f"{outdated_option_used}_{option} setting is deprecated. It will be removed "
+            f"in the future, please use OPENWISP_NETWORK_TOPOLOGY_{option} instead."
         )
-        return getattr(settings, f'{outdated_option_used}_{option}')
-    return getattr(settings, f'OPENWISP_NETWORK_TOPOLOGY_{option}', default)
+        return getattr(settings, f"{outdated_option_used}_{option}")
+    return getattr(settings, f"OPENWISP_NETWORK_TOPOLOGY_{option}", default)
 
 
 DEFAULT_PARSERS = [
-    ('netdiff.OlsrParser', 'OLSRd (txtinfo/jsoninfo)'),
-    ('netdiff.BatmanParser', 'batman-advanced (jsondoc/txtinfo)'),
-    ('netdiff.BmxParser', 'BMX6 (q6m)'),
-    ('netdiff.NetJsonParser', 'NetJSON NetworkGraph'),
-    ('netdiff.CnmlParser', 'CNML 1.0'),
-    ('netdiff.OpenvpnParser', 'OpenVPN'),
-    ('netdiff.WireguardParser', 'Wireguard'),
-    ('netdiff.ZeroTierParser', 'ZeroTier'),
+    ("netdiff.OlsrParser", "OLSRd (txtinfo/jsoninfo)"),
+    ("netdiff.BatmanParser", "batman-advanced (jsondoc/txtinfo)"),
+    ("netdiff.BmxParser", "BMX6 (q6m)"),
+    ("netdiff.NetJsonParser", "NetJSON NetworkGraph"),
+    ("netdiff.CnmlParser", "CNML 1.0"),
+    ("netdiff.OpenvpnParser", "OpenVPN"),
+    ("netdiff.WireguardParser", "Wireguard"),
+    ("netdiff.ZeroTierParser", "ZeroTier"),
 ]
 
-PARSERS = DEFAULT_PARSERS + get_settings_value('PARSERS', [])
-SIGNALS = get_settings_value('SIGNALS', None)
-TIMEOUT = get_settings_value('TIMEOUT', 8)
-LINK_EXPIRATION = get_settings_value('LINK_EXPIRATION', 60)
-NODE_EXPIRATION = get_settings_value('NODE_EXPIRATION', False)
-VISUALIZER_CSS = get_settings_value('VISUALIZER_CSS', 'netjsongraph/css/style.css')
-TOPOLOGY_API_URLCONF = get_settings_value('API_URLCONF', None)
-TOPOLOGY_API_BASEURL = get_settings_value('API_BASEURL', None)
-TOPOLOGY_API_AUTH_REQUIRED = get_settings_value('API_AUTH_REQUIRED', True)
+PARSERS = DEFAULT_PARSERS + get_settings_value("PARSERS", [])
+SIGNALS = get_settings_value("SIGNALS", None)
+TIMEOUT = get_settings_value("TIMEOUT", 8)
+LINK_EXPIRATION = get_settings_value("LINK_EXPIRATION", 60)
+NODE_EXPIRATION = get_settings_value("NODE_EXPIRATION", False)
+VISUALIZER_CSS = get_settings_value("VISUALIZER_CSS", "netjsongraph/css/style.css")
+TOPOLOGY_API_URLCONF = get_settings_value("API_URLCONF", None)
+TOPOLOGY_API_BASEURL = get_settings_value("API_BASEURL", None)
+TOPOLOGY_API_AUTH_REQUIRED = get_settings_value("API_AUTH_REQUIRED", True)
diff --git a/openwisp_network_topology/signals.py b/openwisp_network_topology/signals.py
index 0ed6ae90..e8efca8b 100644
--- a/openwisp_network_topology/signals.py
+++ b/openwisp_network_topology/signals.py
@@ -11,6 +11,6 @@
 def broadcast_topology(topology, *args, **kwargs):
     channel_layer = layers.get_channel_layer()
     async_to_sync(channel_layer.group_send)(
-        f'topology-{topology.pk}',
-        {'type': 'send_topology_update', 'data': topology.json()},
+        f"topology-{topology.pk}",
+        {"type": "send_topology_update", "data": topology.json()},
     )
diff --git a/openwisp_network_topology/tasks.py b/openwisp_network_topology/tasks.py
index 01d713b0..4ffc80fc 100644
--- a/openwisp_network_topology/tasks.py
+++ b/openwisp_network_topology/tasks.py
@@ -20,7 +20,7 @@ def handle_update_topology(topology_pk, diff):
         diff (str):
         A dict containing the network topology diff.
     """
-    Topology = load_model('topology', 'Topology')
+    Topology = load_model("topology", "Topology")
     try:
         topology = Topology.objects.get(pk=topology_pk)
     except ObjectDoesNotExist as e:
diff --git a/openwisp_network_topology/tests/test_admin.py b/openwisp_network_topology/tests/test_admin.py
index 7a03ad02..256c35e4 100644
--- a/openwisp_network_topology/tests/test_admin.py
+++ b/openwisp_network_topology/tests/test_admin.py
@@ -14,43 +14,43 @@
 from ..admin import TopologyAdmin
 from .utils import CreateGraphObjectsMixin, CreateOrgMixin, LoadMixin
 
-Link = swapper.load_model('topology', 'Link')
-Node = swapper.load_model('topology', 'Node')
-Topology = swapper.load_model('topology', 'Topology')
+Link = swapper.load_model("topology", "Link")
+Node = swapper.load_model("topology", "Node")
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TestAdmin(CreateGraphObjectsMixin, CreateOrgMixin, LoadMixin, TestCase):
-    module = 'openwisp_network_topology'
-    app_label = 'topology'
+    module = "openwisp_network_topology"
+    app_label = "topology"
     topology_model = Topology
     link_model = Link
     node_model = Node
     user_model = get_user_model()
-    fixtures = ['test_users.json']
-    api_urls_path = 'api.urls'
+    fixtures = ["test_users.json"]
+    api_urls_path = "api.urls"
 
     @property
     def prefix(self):
-        return 'admin:{0}'.format(self.app_label)
+        return "admin:{0}".format(self.app_label)
 
     def setUp(self):
         org = self._create_org()
         t = self._create_topology(organization=org)
         self._create_node(
-            label='node1', addresses=['192.168.0.1'], topology=t, organization=org
+            label="node1", addresses=["192.168.0.1"], topology=t, organization=org
         )
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t, organization=org
+            label="node2", addresses=["192.168.0.2"], topology=t, organization=org
         )
-        self.client.force_login(self.user_model.objects.get(username='admin'))
-        self.changelist_path = reverse('{0}_topology_changelist'.format(self.prefix))
+        self.client.force_login(self.user_model.objects.get(username="admin"))
+        self.changelist_path = reverse("{0}_topology_changelist".format(self.prefix))
 
     def test_unpublish_selected(self):
         t = self.topology_model.objects.first()
         self.assertEqual(t.published, True)
         self.client.post(
             self.changelist_path,
-            {'action': 'unpublish_selected', '_selected_action': str(t.pk)},
+            {"action": "unpublish_selected", "_selected_action": str(t.pk)},
         )
         t.refresh_from_db()
         self.assertEqual(t.published, False)
@@ -61,7 +61,7 @@ def test_publish_selected(self):
         t.save()
         self.client.post(
             self.changelist_path,
-            {'action': 'publish_selected', '_selected_action': str(t.pk)},
+            {"action": "publish_selected", "_selected_action": str(t.pk)},
         )
         t.refresh_from_db()
         self.assertEqual(t.published, True)
@@ -69,18 +69,18 @@ def test_publish_selected(self):
     @responses.activate
     def test_update_selected(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         self.client.post(
             self.changelist_path,
-            {'action': 'update_selected', '_selected_action': str(t.pk)},
+            {"action": "update_selected", "_selected_action": str(t.pk)},
         )
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
@@ -89,116 +89,116 @@ def test_update_selected(self):
     @responses.activate
     def test_update_selected_failed(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
+            "http://127.0.0.1:9090",
             body='{"error": "not found"}',
             status=404,
-            content_type='application/json',
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         response = self.client.post(
             self.changelist_path,
-            {'action': 'update_selected', '_selected_action': str(t.pk)},
+            {"action": "update_selected", "_selected_action": str(t.pk)},
             follow=True,
         )
         self.assertEqual(self.node_model.objects.count(), 0)
         self.assertEqual(self.link_model.objects.count(), 0)
-        message = list(response.context['messages'])[0]
-        self.assertEqual(message.tags, 'error')
-        self.assertIn('not updated', message.message)
+        message = list(response.context["messages"])[0]
+        self.assertEqual(message.tags, "error")
+        self.assertIn("not updated", message.message)
 
     def test_topology_viewonsite(self):
         topology = self.topology_model.objects.first()
-        path = reverse('{0}_topology_change'.format(self.prefix), args=[topology.pk])
+        path = reverse("{0}_topology_change".format(self.prefix), args=[topology.pk])
         response = self.client.get(path)
-        self.assertContains(response, 'View on site')
+        self.assertContains(response, "View on site")
         # Pattern for the link
-        pattern = '{0}{1}'.format(r'/admin/r/[0-9][0-9]?/', f'{topology.pk}')
+        pattern = "{0}{1}".format(r"/admin/r/[0-9][0-9]?/", f"{topology.pk}")
         self.assertTrue(bool(re.compile(pattern).search(str(response.content))))
 
     def test_topology_receive_url(self):
         t = self.topology_model.objects.first()
-        t.strategy = 'receive'
+        t.strategy = "receive"
         t.save()
-        path = reverse('{0}_topology_change'.format(self.prefix), args=[t.pk])
+        path = reverse("{0}_topology_change".format(self.prefix), args=[t.pk])
         response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertContains(response, 'field-receive_url')
+        self.assertContains(response, "field-receive_url")
 
     def test_custom_topology_receive_url(self):
         t = self.topology_model.objects.first()
-        t.strategy = 'receive'
+        t.strategy = "receive"
         t.save()
-        path = reverse('{0}_topology_change'.format(self.prefix), args=[t.pk])
+        path = reverse("{0}_topology_change".format(self.prefix), args=[t.pk])
         # No change in URL Test
-        receive_path = f'network-topology/topology/{t.pk}/receive/'
+        receive_path = f"network-topology/topology/{t.pk}/receive/"
         response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertContains(response, 'field-receive_url')
-        self.assertContains(response, f'http://testserver/api/v1/{receive_path}')
+        self.assertContains(response, "field-receive_url")
+        self.assertContains(response, f"http://testserver/api/v1/{receive_path}")
         # Change URL Test
-        TopologyAdmin.receive_url_baseurl = 'http://changedurlbase'
+        TopologyAdmin.receive_url_baseurl = "http://changedurlbase"
         response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertContains(response, 'field-receive_url')
-        self.assertContains(response, f'http://changedurlbase/api/v1/{receive_path}')
+        self.assertContains(response, "field-receive_url")
+        self.assertContains(response, f"http://changedurlbase/api/v1/{receive_path}")
         # Change URLConf Test
-        TopologyAdmin.receive_url_urlconf = '{}.{}'.format(
+        TopologyAdmin.receive_url_urlconf = "{}.{}".format(
             self.module, self.api_urls_path
         )
         response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertContains(response, 'field-receive_url')
-        self.assertContains(response, f'http://changedurlbase/{receive_path}')
+        self.assertContains(response, "field-receive_url")
+        self.assertContains(response, f"http://changedurlbase/{receive_path}")
         # Reset test options
         TopologyAdmin.receive_url_baseurl = None
         TopologyAdmin.receive_url_urlconf = None
 
     def test_node_change_form(self):
         n = self.node_model.objects.first()
-        path = reverse('{0}_node_change'.format(self.prefix), args=[n.pk])
+        path = reverse("{0}_node_change".format(self.prefix), args=[n.pk])
         response = self.client.get(path)
-        self.assertContains(response, 'Links to other nodes')
-        self.assertNotContains(response, 'organization_id')
+        self.assertContains(response, "Links to other nodes")
+        self.assertNotContains(response, "organization_id")
         self.assertContains(response, n.topology.organization.name)
 
     def test_node_change_list_queries(self):
-        path = reverse('{0}_node_changelist'.format(self.prefix))
+        path = reverse("{0}_node_changelist".format(self.prefix))
         with self.assertNumQueries(5):
             self.client.get(path)
 
     def test_link_change_list_queries(self):
         t = Topology.objects.first()
-        n1 = self._create_node(label='node1org1', topology=t)
-        n2 = self._create_node(label='node2org1', topology=t)
+        n1 = self._create_node(label="node1org1", topology=t)
+        n2 = self._create_node(label="node2org1", topology=t)
         self._create_link(topology=t, source=n1, target=n2)
-        path = reverse('{0}_link_changelist'.format(self.prefix))
+        path = reverse("{0}_link_changelist".format(self.prefix))
         with self.assertNumQueries(5):
             self.client.get(path)
 
     def test_link_change_form(self):
         t = Topology.objects.first()
-        n1 = self._create_node(label='node1org1', topology=t)
-        n2 = self._create_node(label='node2org1', topology=t)
+        n1 = self._create_node(label="node1org1", topology=t)
+        n2 = self._create_node(label="node2org1", topology=t)
         link = self._create_link(topology=t, source=n1, target=n2)
-        path = reverse('{0}_link_change'.format(self.prefix), args=[link.pk])
+        path = reverse("{0}_link_change".format(self.prefix), args=[link.pk])
         response = self.client.get(path)
-        self.assertNotContains(response, 'organization_id')
+        self.assertNotContains(response, "organization_id")
         self.assertContains(response, link.topology.organization.name)
 
     def test_node_add(self):
-        path = reverse('{0}_node_add'.format(self.prefix))
+        path = reverse("{0}_node_add".format(self.prefix))
         response = self.client.get(path)
-        self.assertNotContains(response, 'Links to other nodes')
+        self.assertNotContains(response, "Links to other nodes")
 
     def test_topology_change_form(self):
         topology = self.topology_model.objects.first()
-        path = reverse('{0}_topology_change'.format(self.prefix), args=[topology.pk])
+        path = reverse("{0}_topology_change".format(self.prefix), args=[topology.pk])
         response = self.client.get(path)
-        self.assertContains(response, 'View topology graph')
+        self.assertContains(response, "View topology graph")
         self.assertContains(
             response, '<div class="readonly">{0}</div>'.format(topology.pk)
         )
@@ -206,71 +206,71 @@ def test_topology_change_form(self):
 
     def test_topology_visualize_view(self):
         t = self.topology_model.objects.first()
-        path = reverse('{0}_topology_visualize'.format(self.prefix), args=[t.pk])
+        path = reverse("{0}_topology_visualize".format(self.prefix), args=[t.pk])
         response = self.client.get(path)
-        self.assertContains(response, 'new NetJSONGraph(')
+        self.assertContains(response, "new NetJSONGraph(")
 
     def test_update_selected_receive_topology(self):
         t = self.topology_model.objects.first()
-        t.label = 'test receive'
-        t.parser = 'netdiff.NetJsonParser'
-        t.strategy = 'receive'
+        t.label = "test receive"
+        t.parser = "netdiff.NetJsonParser"
+        t.strategy = "receive"
         t.save()
         response = self.client.post(
             self.changelist_path,
-            {'action': 'update_selected', '_selected_action': str(t.pk)},
+            {"action": "update_selected", "_selected_action": str(t.pk)},
             follow=True,
         )
-        message = list(response.context['messages'])[0]
-        self.assertEqual('warning', message.tags)
-        self.assertIn('1 topology was ignored', message.message)
+        message = list(response.context["messages"])[0]
+        self.assertEqual("warning", message.tags)
+        self.assertIn("1 topology was ignored", message.message)
 
     def _test_properties_field(self, model, obj):
-        with self.subTest('test old properties readonly'):
+        with self.subTest("test old properties readonly"):
             content = 'readonly_properties">'
-            r = self.client.get(reverse(f'{self.prefix}_{model}_add'))
+            r = self.client.get(reverse(f"{self.prefix}_{model}_add"))
             self.assertEqual(r.status_code, 200)
             self.assertContains(r, content)
 
-        with self.subTest('test old properties display in list'):
-            path = reverse(f'{self.prefix}_{model}_change', args=[obj.pk])
+        with self.subTest("test old properties display in list"):
+            path = reverse(f"{self.prefix}_{model}_change", args=[obj.pk])
             r = self.client.get(path)
             self.assertEqual(r.status_code, 200)
-            content = '<p><strong>Gateway</strong>: False</p>'
+            content = "<p><strong>Gateway</strong>: False</p>"
             self.assertContains(r, content)
 
-        with self.subTest('test user properties diplay in flat json widgets'):
-            r = self.client.get(reverse(f'{self.prefix}_{model}_add'))
+        with self.subTest("test user properties diplay in flat json widgets"):
+            r = self.client.get(reverse(f"{self.prefix}_{model}_add"))
             self.assertEqual(r.status_code, 200)
-            self.assertContains(r, 'flat-json-user_properties')
+            self.assertContains(r, "flat-json-user_properties")
 
     def test_node_user_properties_field(self):
         t = Topology.objects.first()
-        n = self._create_node(label='node1org1', topology=t)
-        n.properties = {'gateway': False}
+        n = self._create_node(label="node1org1", topology=t)
+        n.properties = {"gateway": False}
         n.full_clean()
         n.save()
-        self._test_properties_field('node', n)
+        self._test_properties_field("node", n)
 
     def test_link_user_properties_field(self):
         t = Topology.objects.first()
-        n1 = self._create_node(label='node1org1', topology=t)
-        n2 = self._create_node(label='node2org1', topology=t)
+        n1 = self._create_node(label="node1org1", topology=t)
+        n2 = self._create_node(label="node2org1", topology=t)
         li = self._create_link(topology=t, source=n1, target=n2)
-        li.properties = {'gateway': False}
+        li.properties = {"gateway": False}
         li.full_clean()
         li.save()
-        self._test_properties_field('link', li)
+        self._test_properties_field("link", li)
 
     def test_admin_menu_groups(self):
         # Test menu group (openwisp-utils menu group) for Topology and Link
         # and Node
-        self.client.force_login(self.user_model.objects.get(username='admin'))
-        response = self.client.get(reverse('admin:index'))
-        models = ['topology', 'node', 'link']
+        self.client.force_login(self.user_model.objects.get(username="admin"))
+        response = self.client.get(reverse("admin:index"))
+        models = ["topology", "node", "link"]
         for model in models:
-            with self.subTest('test menu group link for {model} model'):
-                url = reverse(f'admin:{self.app_label}_{model}_changelist')
+            with self.subTest("test menu group link for {model} model"):
+                url = reverse(f"admin:{self.app_label}_{model}_changelist")
                 self.assertContains(response, f'class="mg-link" href="{url}"')
         with self.subTest('test "networking topology" group is registered'):
             self.assertContains(
@@ -287,29 +287,29 @@ class TestMultitenantAdmin(
     TestOrganizationMixin,
     TestCase,
 ):
-    app_label = 'topology'
+    app_label = "topology"
     topology_model = Topology
     node_model = Node
     link_model = Link
 
     def _create_multitenancy_test_env(self):
-        org1 = self._create_org(name='test1org')
-        org2 = self._create_org(name='test2org')
-        inactive = self._create_org(name='inactive-org', is_active=False)
+        org1 = self._create_org(name="test1org")
+        org2 = self._create_org(name="test2org")
+        inactive = self._create_org(name="inactive-org", is_active=False)
         operator = self._create_operator(organizations=[org1, inactive])
         administrator = self._create_administrator(organizations=[org1, inactive])
-        t1 = self._create_topology(label='topology1org', organization=org1)
-        t2 = self._create_topology(label='topology2org', organization=org2)
-        t3 = self._create_topology(label='topology3org', organization=inactive)
-        n11 = self._create_node(label='node1org1', topology=t1, organization=org1)
-        n12 = self._create_node(label='node2org1', topology=t1, organization=org1)
-        n21 = self._create_node(label='node1org2', topology=t2, organization=org2)
-        n22 = self._create_node(label='node2org2', topology=t2, organization=org2)
+        t1 = self._create_topology(label="topology1org", organization=org1)
+        t2 = self._create_topology(label="topology2org", organization=org2)
+        t3 = self._create_topology(label="topology3org", organization=inactive)
+        n11 = self._create_node(label="node1org1", topology=t1, organization=org1)
+        n12 = self._create_node(label="node2org1", topology=t1, organization=org1)
+        n21 = self._create_node(label="node1org2", topology=t2, organization=org2)
+        n22 = self._create_node(label="node2org2", topology=t2, organization=org2)
         n31 = self._create_node(
-            label='node1inactive', topology=t3, organization=inactive
+            label="node1inactive", topology=t3, organization=inactive
         )
         n32 = self._create_node(
-            label='node2inactive', topology=t3, organization=inactive
+            label="node2inactive", topology=t3, organization=inactive
         )
         l1 = self._create_link(topology=t1, organization=org1, source=n11, target=n12)
         l2 = self._create_link(topology=t2, organization=org2, source=n21, target=n22)
@@ -338,122 +338,122 @@ def _create_multitenancy_test_env(self):
         return data
 
     def _get_autocomplete_view_path(
-        self, app_label, model_name, field_name, path='admin:ow-auto-filter'
+        self, app_label, model_name, field_name, path="admin:ow-auto-filter"
     ):
         return (
-            f'{reverse(path)}?app_label={app_label}'
-            f'&model_name={model_name}&field_name={field_name}'
+            f"{reverse(path)}?app_label={app_label}"
+            f"&model_name={model_name}&field_name={field_name}"
         )
 
     def test_topology_queryset(self):
         data = self._create_multitenancy_test_env()
         perm = Permission.objects.get_by_natural_key(
-            'delete_topology', self.app_label, self.topology_model.__name__.lower()
+            "delete_topology", self.app_label, self.topology_model.__name__.lower()
         )
-        data['operator'].user_permissions.remove(perm)
+        data["operator"].user_permissions.remove(perm)
         self._test_multitenant_admin(
-            url=reverse(f'admin:{self.app_label}_topology_changelist'),
-            visible=[data['t1'].label, data['org1'].name],
-            hidden=[data['t2'].label, data['org2'].name, data['t3_inactive'].label],
+            url=reverse(f"admin:{self.app_label}_topology_changelist"),
+            visible=[data["t1"].label, data["org1"].name],
+            hidden=[data["t2"].label, data["org2"].name, data["t3_inactive"].label],
         )
 
     def test_topology_organization_fk_autocomplete_view(self):
         data = self._create_multitenancy_test_env()
         self._test_multitenant_admin(
             url=self._get_autocomplete_view_path(
-                self.app_label, 'topology', 'organization'
+                self.app_label, "topology", "organization"
             ),
-            visible=[data['org1'].name],
-            hidden=[data['org2'].name, data['inactive']],
+            visible=[data["org1"].name],
+            hidden=[data["org2"].name, data["inactive"]],
             administrator=True,
         )
 
     def test_node_queryset(self):
         data = self._create_multitenancy_test_env()
         self._test_multitenant_admin(
-            url=reverse(f'admin:{self.app_label}_node_changelist'),
-            visible=[data['n11'].label, data['n12'].label, data['org1'].name],
+            url=reverse(f"admin:{self.app_label}_node_changelist"),
+            visible=[data["n11"].label, data["n12"].label, data["org1"].name],
             hidden=[
-                data['n21'].label,
-                data['n22'].label,
-                data['org2'].name,
-                data['n31'].label,
-                data['n32'].label,
-                data['inactive'],
+                data["n21"].label,
+                data["n22"].label,
+                data["org2"].name,
+                data["n31"].label,
+                data["n32"].label,
+                data["inactive"],
             ],
         )
 
     def test_node_organization_fk_queryset(self):
         self._create_multitenancy_test_env()
-        self._login(username='operator', password='tester')
-        response = self.client.get(reverse(f'admin:{self.app_label}_node_add'))
-        self.assertNotContains(response, 'organization_id')
+        self._login(username="operator", password="tester")
+        response = self.client.get(reverse(f"admin:{self.app_label}_node_add"))
+        self.assertNotContains(response, "organization_id")
 
     def test_link_queryset(self):
         data = self._create_multitenancy_test_env()
         self._test_multitenant_admin(
-            url=reverse(f'admin:{self.app_label}_link_changelist'),
-            visible=[str(data['l1']), data['org1'].name],
-            hidden=[str(data['l2']), data['org2'].name, str(data['l3_inactive'])],
+            url=reverse(f"admin:{self.app_label}_link_changelist"),
+            visible=[str(data["l1"]), data["org1"].name],
+            hidden=[str(data["l2"]), data["org2"].name, str(data["l3_inactive"])],
         )
 
     def test_link_organization_fk_queryset(self):
         self._create_multitenancy_test_env()
-        self._login(username='operator', password='tester')
-        response = self.client.get(reverse(f'admin:{self.app_label}_link_add'))
-        self.assertNotContains(response, 'organization_id')
+        self._login(username="operator", password="tester")
+        response = self.client.get(reverse(f"admin:{self.app_label}_link_add"))
+        self.assertNotContains(response, "organization_id")
 
     def test_node_topology_fk_autocomplete_view(self):
         data = self._create_multitenancy_test_env()
         self._test_multitenant_admin(
             url=self._get_autocomplete_view_path(
-                self.app_label, 'node', 'topology', path='admin:autocomplete'
+                self.app_label, "node", "topology", path="admin:autocomplete"
             ),
-            visible=[data['t1'].label],
-            hidden=[data['t2'].label, data['t3_inactive'].label],
+            visible=[data["t1"].label],
+            hidden=[data["t2"].label, data["t3_inactive"].label],
         )
 
     def test_link_topology_fk_autocomplete_view(self):
         data = self._create_multitenancy_test_env()
         self._test_multitenant_admin(
             url=self._get_autocomplete_view_path(
-                self.app_label, 'link', 'topology', path='admin:autocomplete'
+                self.app_label, "link", "topology", path="admin:autocomplete"
             ),
-            visible=[data['t1'].label],
-            hidden=[data['t2'].label, data['t3_inactive'].label],
+            visible=[data["t1"].label],
+            hidden=[data["t2"].label, data["t3_inactive"].label],
         )
 
     def test_node_topology_autocomplete_filter(self):
         data = self._create_multitenancy_test_env()
-        t_special = self._create_topology(label='special', organization=data['org1'])
+        t_special = self._create_topology(label="special", organization=data["org1"])
         self._test_multitenant_admin(
-            url=self._get_autocomplete_view_path(self.app_label, 'node', 'topology'),
-            visible=[data['t1'].label, t_special.label],
-            hidden=[data['t2'].label, data['t3_inactive'].label],
+            url=self._get_autocomplete_view_path(self.app_label, "node", "topology"),
+            visible=[data["t1"].label, t_special.label],
+            hidden=[data["t2"].label, data["t3_inactive"].label],
         )
 
     def test_link_topology_autocomplete_filter(self):
         data = self._create_multitenancy_test_env()
-        t_special = self._create_topology(label='special', organization=data['org1'])
+        t_special = self._create_topology(label="special", organization=data["org1"])
         self._test_multitenant_admin(
-            url=self._get_autocomplete_view_path(self.app_label, 'link', 'topology'),
-            visible=[data['t1'].label, t_special.label],
-            hidden=[data['t2'].label, data['t3_inactive'].label],
+            url=self._get_autocomplete_view_path(self.app_label, "link", "topology"),
+            visible=[data["t1"].label, t_special.label],
+            hidden=[data["t2"].label, data["t3_inactive"].label],
         )
 
-    @patch.object(Topology, 'update')
+    @patch.object(Topology, "update")
     def test_update_selected_action_perms(self, *args):
         org = self._get_org()
         user = self._create_user(is_staff=True)
         self._create_org_user(user=user, organization=org, is_admin=True)
         topology = self._create_topology(organization=org)
         self._test_action_permission(
-            path=reverse(f'admin:{self.app_label}_topology_changelist'),
-            action='update_selected',
+            path=reverse(f"admin:{self.app_label}_topology_changelist"),
+            action="update_selected",
             user=user,
             obj=topology,
-            message='1 topology was successfully updated',
-            required_perms=['change'],
+            message="1 topology was successfully updated",
+            required_perms=["change"],
         )
 
     def test_publish_selected_action_perms(self):
@@ -462,12 +462,12 @@ def test_publish_selected_action_perms(self):
         self._create_org_user(user=user, organization=org, is_admin=True)
         topology = self._create_topology(organization=org)
         self._test_action_permission(
-            path=reverse(f'admin:{self.app_label}_topology_changelist'),
-            action='publish_selected',
+            path=reverse(f"admin:{self.app_label}_topology_changelist"),
+            action="publish_selected",
             user=user,
             obj=topology,
-            message='1 topology was successfully published',
-            required_perms=['change'],
+            message="1 topology was successfully published",
+            required_perms=["change"],
         )
 
     def test_unpublish_selected_action_perms(self):
@@ -476,10 +476,10 @@ def test_unpublish_selected_action_perms(self):
         self._create_org_user(user=user, organization=org, is_admin=True)
         topology = self._create_topology(organization=org)
         self._test_action_permission(
-            path=reverse(f'admin:{self.app_label}_topology_changelist'),
-            action='unpublish_selected',
+            path=reverse(f"admin:{self.app_label}_topology_changelist"),
+            action="unpublish_selected",
             user=user,
             obj=topology,
-            message='1 topology was successfully unpublished',
-            required_perms=['change'],
+            message="1 topology was successfully unpublished",
+            required_perms=["change"],
         )
diff --git a/openwisp_network_topology/tests/test_api.py b/openwisp_network_topology/tests/test_api.py
index abd43ef0..93a25a51 100644
--- a/openwisp_network_topology/tests/test_api.py
+++ b/openwisp_network_topology/tests/test_api.py
@@ -13,13 +13,13 @@
 
 from .utils import CreateGraphObjectsMixin, LoadMixin, UnpublishMixin
 
-Link = swapper.load_model('topology', 'Link')
-Node = swapper.load_model('topology', 'Node')
-Snapshot = swapper.load_model('topology', 'Snapshot')
-Topology = swapper.load_model('topology', 'Topology')
-Organization = swapper.load_model('openwisp_users', 'Organization')
-OrganizationUser = swapper.load_model('openwisp_users', 'OrganizationUser')
-Group = swapper.load_model('openwisp_users', 'Group')
+Link = swapper.load_model("topology", "Link")
+Node = swapper.load_model("topology", "Node")
+Snapshot = swapper.load_model("topology", "Snapshot")
+Topology = swapper.load_model("topology", "Topology")
+Organization = swapper.load_model("openwisp_users", "Organization")
+OrganizationUser = swapper.load_model("openwisp_users", "OrganizationUser")
+Group = swapper.load_model("openwisp_users", "Group")
 
 
 class TestApi(
@@ -30,7 +30,7 @@ class TestApi(
     TestOrganizationMixin,
     TestCase,
 ):
-    list_url = reverse('network_collection')
+    list_url = reverse("network_collection")
     topology_model = Topology
     node_model = Node
     link_model = Link
@@ -39,9 +39,9 @@ class TestApi(
     def setUp(self):
         org = self._get_org()
         self.topology = self._create_topology(organization=org)
-        user = self._create_user(username='tester', email='tester@email.com')
-        user.groups.set(Group.objects.filter(name='Operator'))
-        perm = Permission.objects.filter(codename__endswith='topology')
+        user = self._create_user(username="tester", email="tester@email.com")
+        user.groups.set(Group.objects.filter(name="Operator"))
+        perm = Permission.objects.filter(codename__endswith="topology")
         user.user_permissions.add(*perm)
         self._create_org_user(user=user, organization=org, is_admin=True)
         self.node1 = self._create_node(
@@ -64,25 +64,25 @@ def setUp(self):
     @property
     def detail_url(self):
         t = self.topology_model.objects.first()
-        return reverse('network_graph', args=[t.pk])
+        return reverse("network_graph", args=[t.pk])
 
     @property
     def receive_url(self):
         t = self.topology_model.objects.first()
-        path = reverse('receive_topology', args=[t.pk])
-        return f'{path}?key=test'
+        path = reverse("receive_topology", args=[t.pk])
+        return f"{path}?key=test"
 
     @property
     def snapshot_url(self):
         t = self.topology_model.objects.first()
-        path = reverse('network_graph_history', args=[t.pk])
-        return f'{path}?date={self.snapshot_date}'
+        path = reverse("network_graph_history", args=[t.pk])
+        return f"{path}?date={self.snapshot_date}"
 
     def _set_receive(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
-        t.strategy = 'receive'
-        t.key = 'test'
+        t.parser = "netdiff.NetJsonParser"
+        t.strategy = "receive"
+        t.key = "test"
         t.expiration_time = 0
         t.save()
 
@@ -93,201 +93,201 @@ def snapshot_date(self):
 
     def test_list(self):
         response = self.client.get(self.list_url)
-        self.assertEqual(response.data['type'], 'NetworkCollection')
-        self.assertEqual(len(response.data['collection']), 1)
+        self.assertEqual(response.data["type"], "NetworkCollection")
+        self.assertEqual(len(response.data["collection"]), 1)
 
     def test_list_topology_filter(self):
         admin = self._create_admin()
         self.client.force_login(admin)
-        org2 = self._create_org(name='org2')
+        org2 = self._create_org(name="org2")
         self._create_topology(
-            organization=org2, parser='netdiff.OpenvpnParser', strategy='receive'
+            organization=org2, parser="netdiff.OpenvpnParser", strategy="receive"
         )
 
-        with self.subTest('Test without filter'):
+        with self.subTest("Test without filter"):
             response = self.client.get(self.list_url)
-            self.assertEqual(len(response.data['collection']), 2)
+            self.assertEqual(len(response.data["collection"]), 2)
 
-        with self.subTest('Test filter with parser'):
-            response = self.client.get(f'{self.list_url}?parser=netdiff.OpenvpnParser')
-            self.assertEqual(len(response.data['collection']), 1)
+        with self.subTest("Test filter with parser"):
+            response = self.client.get(f"{self.list_url}?parser=netdiff.OpenvpnParser")
+            self.assertEqual(len(response.data["collection"]), 1)
 
-        with self.subTest('Test filter with organization'):
-            response = self.client.get(f'{self.list_url}?organization={org2.pk}')
-            self.assertEqual(len(response.data['collection']), 1)
+        with self.subTest("Test filter with organization"):
+            response = self.client.get(f"{self.list_url}?organization={org2.pk}")
+            self.assertEqual(len(response.data["collection"]), 1)
 
-        with self.subTest('Test filter with organization slug'):
-            response = self.client.get(f'{self.list_url}?organization_slug={org2.slug}')
-            self.assertEqual(len(response.data['collection']), 1)
+        with self.subTest("Test filter with organization slug"):
+            response = self.client.get(f"{self.list_url}?organization_slug={org2.slug}")
+            self.assertEqual(len(response.data["collection"]), 1)
 
-        with self.subTest('Test filter with strategy'):
-            response = self.client.get(f'{self.list_url}?strategy=receive')
-            self.assertEqual(len(response.data['collection']), 1)
+        with self.subTest("Test filter with strategy"):
+            response = self.client.get(f"{self.list_url}?strategy=receive")
+            self.assertEqual(len(response.data["collection"]), 1)
 
     def test_detail(self):
         response = self.client.get(self.detail_url)
-        self.assertEqual(response.data['type'], 'NetworkGraph')
+        self.assertEqual(response.data["type"], "NetworkGraph")
 
     def test_list_include_unpublished(self):
         self._unpublish()
-        path = f'{self.list_url}?include_unpublished=true'
+        path = f"{self.list_url}?include_unpublished=true"
         response = self.client.get(path)
-        self.assertEqual(len(response.data['collection']), 1)
+        self.assertEqual(len(response.data["collection"]), 1)
 
-        path = f'{self.list_url}?published=true'
+        path = f"{self.list_url}?published=true"
         response = self.client.get(path)
-        self.assertEqual(len(response.data['collection']), 0)
+        self.assertEqual(len(response.data["collection"]), 0)
 
     def test_detail_unpublished_topology(self):
         self._unpublish()
-        with self.subTest('Test view returns 404 for unpublished topology'):
+        with self.subTest("Test view returns 404 for unpublished topology"):
             response = self.client.get(self.detail_url)
             self.assertEqual(response.status_code, 404)
 
         with self.subTest('Test "include_unpublished" filter'):
-            path = f'{self.detail_url}?include_unpublished=true'
+            path = f"{self.detail_url}?include_unpublished=true"
             response = self.client.get(path)
             self.assertEqual(response.status_code, 200)
 
     def test_receive(self):
         self._set_receive()
         self.node_model.objects.all().delete()
-        data = self._load('static/netjson-1-link.json')
-        response = self.client.post(self.receive_url, data, content_type='text/plain')
+        data = self._load("static/netjson-1-link.json")
+        response = self.client.post(self.receive_url, data, content_type="text/plain")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['detail'], 'data received successfully')
+        self.assertEqual(response.data["detail"], "data received successfully")
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
 
-    @patch('openwisp_network_topology.tasks.handle_update_topology.delay')
+    @patch("openwisp_network_topology.tasks.handle_update_topology.delay")
     def test_background_topology_update_task(self, mocked_task):
         self._set_receive()
         self.node_model.objects.all().delete()
         topology = self.topology_model.objects.first()
-        data = self._load('static/netjson-1-link.json')
-        response = self.client.post(self.receive_url, data, content_type='text/plain')
+        data = self._load("static/netjson-1-link.json")
+        response = self.client.post(self.receive_url, data, content_type="text/plain")
         mocked_task.assert_called_once_with(topology.pk, topology.diff(data))
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['detail'], 'data received successfully')
+        self.assertEqual(response.data["detail"], "data received successfully")
 
-    @patch('openwisp_network_topology.tasks.logger.warning')
+    @patch("openwisp_network_topology.tasks.logger.warning")
     def test_background_topology_update_task_warning(self, mock_warn):
         invalid_topology_pk = str(uuid4())
-        data = {'test_key': 'test_value'}
+        data = {"test_key": "test_value"}
         handle_update_topology(invalid_topology_pk, data)
         mock_warn.assert_called_once_with(
             f'handle_update_topology("{invalid_topology_pk}") failed: Topology matching query does not exist.'
         )
 
-    @patch('openwisp_network_topology.tasks.handle_update_topology.delay')
+    @patch("openwisp_network_topology.tasks.handle_update_topology.delay")
     def test_handle_update_topology_400_unrecognized_format(self, mocked_task):
         self._set_receive()
         self.node_model.objects.all().delete()
-        data = 'WRONG'
-        response = self.client.post(self.receive_url, data, content_type='text/plain')
+        data = "WRONG"
+        response = self.client.post(self.receive_url, data, content_type="text/plain")
         mocked_task.assert_not_called()
         self.assertEqual(response.status_code, 400)
-        self.assertIn('not recognized', response.data['detail'])
+        self.assertIn("not recognized", response.data["detail"])
 
     def test_receive_404(self):
         # topology is set to FETCH strategy
-        response = self.client.post(self.receive_url, content_type='text/plain')
+        response = self.client.post(self.receive_url, content_type="text/plain")
         self.assertEqual(response.status_code, 404)
 
     def test_receive_415(self):
         self._set_receive()
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         response = self.client.post(
-            self.receive_url, data, content_type='application/xml'
+            self.receive_url, data, content_type="application/xml"
         )
         self.assertEqual(response.status_code, 415)
 
     def test_receive_400_missing_key(self):
         self._set_receive()
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         response = self.client.post(
-            self.receive_url.replace('?key=test', ''), data, content_type='text/plain'
+            self.receive_url.replace("?key=test", ""), data, content_type="text/plain"
         )
         self.assertEqual(response.status_code, 400)
-        self.assertIn('missing required', response.data['detail'])
+        self.assertIn("missing required", response.data["detail"])
 
     def test_receive_400_unrecognized_format(self):
         self._set_receive()
         self.node_model.objects.all().delete()
-        data = 'WRONG'
-        response = self.client.post(self.receive_url, data, content_type='text/plain')
+        data = "WRONG"
+        response = self.client.post(self.receive_url, data, content_type="text/plain")
         self.assertEqual(response.status_code, 400)
-        self.assertIn('not recognized', response.data['detail'])
+        self.assertIn("not recognized", response.data["detail"])
 
     def test_receive_403(self):
         self._set_receive()
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         response = self.client.post(
-            self.receive_url.replace('?key=test', '?key=wrong'),
+            self.receive_url.replace("?key=test", "?key=wrong"),
             data,
-            content_type='text/plain',
+            content_type="text/plain",
         )
         self.assertEqual(response.status_code, 403)
 
     def test_receive_options(self):
         self._set_receive()
         response = self.client.options(self.receive_url)
-        self.assertEqual(response.data['parses'], ['text/plain'])
+        self.assertEqual(response.data["parses"], ["text/plain"])
 
     def test_snapshot(self):
         response = self.client.get(self.snapshot_url)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['type'], 'NetworkGraph')
+        self.assertEqual(response.data["type"], "NetworkGraph")
 
     def test_snapshot_missing_date_400(self):
         date = self.snapshot_date
         response = self.client.get(
-            self.snapshot_url.replace('?date={0}'.format(date), '')
+            self.snapshot_url.replace("?date={0}".format(date), "")
         )
         self.assertEqual(response.status_code, 400)
-        self.assertEqual(response.data['detail'], 'missing required "date" parameter')
+        self.assertEqual(response.data["detail"], 'missing required "date" parameter')
 
     def test_snapshot_invalid_date_403(self):
         date = self.snapshot_date
-        url = self.snapshot_url.replace('?date={0}'.format(date), '?date=wrong-date')
+        url = self.snapshot_url.replace("?date={0}".format(date), "?date=wrong-date")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 403)
-        self.assertEqual(response.data['detail'], 'invalid date supplied')
+        self.assertEqual(response.data["detail"], "invalid date supplied")
 
     def test_snapshot_no_snapshot_404(self):
         date = self.snapshot_date
-        url = self.snapshot_url.replace('?date={0}'.format(date), '?date=2001-01-01')
+        url = self.snapshot_url.replace("?date={0}".format(date), "?date=2001-01-01")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 404)
-        self.assertIn('no snapshot found', response.data['detail'])
+        self.assertIn("no snapshot found", response.data["detail"])
 
     def _test_api_with_unauthenticated_user(self, url):
         self.client.logout()
         r = self.client.get(url)
         self.assertEqual(r.status_code, 403)
         self.assertEqual(
-            r.data['detail'], 'Authentication credentials were not provided.'
+            r.data["detail"], "Authentication credentials were not provided."
         )
         self.assertEqual(len(r.data), 1)
 
     def _test_api_with_not_a_manager_user(self, user, url, has_detail=True):
         OrganizationUser.objects.filter(user=user).delete()
-        perm = Permission.objects.filter(codename__endswith='topology')
+        perm = Permission.objects.filter(codename__endswith="topology")
         user.user_permissions.add(*perm)
         self.client.force_login(user)
         r = self.client.get(url)
         if not has_detail:
             self.assertEqual(r.status_code, 200)
-            self.assertEqual(r.data['type'], 'NetworkCollection')
-            self.assertEqual(len(r.data['collection']), 0)
+            self.assertEqual(r.data["type"], "NetworkCollection")
+            self.assertEqual(len(r.data["collection"]), 0)
             self.assertNotEqual(Topology.objects.all().count(), 0)
         else:
             detail = (
-                'User is not a manager of the organization to '
-                'which the requested resource belongs.'
+                "User is not a manager of the organization to "
+                "which the requested resource belongs."
             )
             self.assertEqual(r.status_code, 403)
-            self.assertEqual(r.data['detail'], detail)
+            self.assertEqual(r.data["detail"], detail)
             self.assertEqual(len(r.data), 1)
 
     def _test_api_with_not_permitted_user(self, user, url):
@@ -297,23 +297,23 @@ def _test_api_with_not_permitted_user(self, user, url):
         r = self.client.get(url)
         self.assertEqual(r.status_code, 403)
         self.assertEqual(
-            r.data['detail'], 'You do not have permission to perform this action.'
+            r.data["detail"], "You do not have permission to perform this action."
         )
         self.assertEqual(len(r.data), 1)
 
     def test_modelpermission_class_with_change_perm(self):
         t = self.topology_model.objects.first()
-        user = self._create_user(username='list-user', email='list@email.com')
+        user = self._create_user(username="list-user", email="list@email.com")
         self._create_org_user(user=user, organization=t.organization, is_admin=True)
-        change_perm = Permission.objects.filter(codename='change_topology')
+        change_perm = Permission.objects.filter(codename="change_topology")
         user.user_permissions.add(*change_perm)
         self.client.force_login(user)
-        with self.subTest('List url'):
+        with self.subTest("List url"):
             url = self.list_url
             with self.assertNumQueries(7):
                 response = self.client.get(url)
             self.assertEqual(response.status_code, 200)
-        with self.subTest('Detail url'):
+        with self.subTest("Detail url"):
             url = self.detail_url
             with self.assertNumQueries(7):
                 response = self.client.get(url)
@@ -321,17 +321,17 @@ def test_modelpermission_class_with_change_perm(self):
 
     def test_modelpermission_class_with_view_perm(self):
         t = self.topology_model.objects.first()
-        user = self._create_user(username='list-user', email='list@email.com')
+        user = self._create_user(username="list-user", email="list@email.com")
         self._create_org_user(user=user, organization=t.organization, is_admin=True)
-        view_perm = Permission.objects.filter(codename='view_topology')
+        view_perm = Permission.objects.filter(codename="view_topology")
         user.user_permissions.add(*view_perm)
         self.client.force_login(user)
-        with self.subTest('List url'):
+        with self.subTest("List url"):
             url = self.list_url
             with self.assertNumQueries(7):
                 response = self.client.get(url)
             self.assertEqual(response.status_code, 200)
-        with self.subTest('Detail url'):
+        with self.subTest("Detail url"):
             url = self.detail_url
             with self.assertNumQueries(7):
                 response = self.client.get(url)
@@ -339,394 +339,394 @@ def test_modelpermission_class_with_view_perm(self):
 
     def test_modelpermission_class_with_no_perm(self):
         t = self.topology_model.objects.first()
-        user = self._create_user(username='list-user', email='list@email.com')
+        user = self._create_user(username="list-user", email="list@email.com")
         self._create_org_user(user=user, organization=t.organization, is_admin=True)
         self.client.force_login(user)
-        with self.subTest('List url'):
+        with self.subTest("List url"):
             url = self.list_url
             with self.assertNumQueries(4):
                 response = self.client.get(url)
             self.assertEqual(response.status_code, 403)
-        with self.subTest('Detail url'):
+        with self.subTest("Detail url"):
             url = self.detail_url
             with self.assertNumQueries(4):
                 response = self.client.get(url)
             self.assertEqual(response.status_code, 403)
 
     def test_list_with_auth_enabled(self):
-        user = self._create_user(username='list-user', email='list@email.com')
-        with self.subTest('test api with unauthenticated user'):
+        user = self._create_user(username="list-user", email="list@email.com")
+        with self.subTest("test api with unauthenticated user"):
             self._test_api_with_unauthenticated_user(self.list_url)
 
-        with self.subTest('test api with not a permitted user'):
+        with self.subTest("test api with not a permitted user"):
             self._test_api_with_not_permitted_user(user, self.list_url)
 
-        with self.subTest('test api with not a member user'):
+        with self.subTest("test api with not a member user"):
             self._test_api_with_not_a_manager_user(user, self.list_url)
 
     def test_detail_with_auth_enabled(self):
-        user = self._create_user(username='detail-user', email='detail@email.com')
-        with self.subTest('test api with unauthenticated user'):
+        user = self._create_user(username="detail-user", email="detail@email.com")
+        with self.subTest("test api with unauthenticated user"):
             self._test_api_with_unauthenticated_user(self.detail_url)
 
-        with self.subTest('test api with not a permitted user'):
+        with self.subTest("test api with not a permitted user"):
             self._test_api_with_not_permitted_user(user, self.detail_url)
 
-        with self.subTest('test api with not a member user'):
+        with self.subTest("test api with not a member user"):
             self._test_api_with_not_a_manager_user(user, self.detail_url)
 
     def test_snapshot_with_auth_enabled(self):
-        user = self._create_user(username='snapshot-user', email='snapshot@email.com')
-        with self.subTest('test api with unauthenticated user'):
+        user = self._create_user(username="snapshot-user", email="snapshot@email.com")
+        with self.subTest("test api with unauthenticated user"):
             self._test_api_with_unauthenticated_user(self.snapshot_url)
 
-        with self.subTest('test api with not a permitted user'):
+        with self.subTest("test api with not a permitted user"):
             self._test_api_with_not_permitted_user(user, self.snapshot_url)
 
-        with self.subTest('test api with not a member user'):
+        with self.subTest("test api with not a member user"):
             self._test_api_with_not_a_manager_user(user, self.snapshot_url)
 
     def _successful_api_tests(self):
-        with self.subTest('test receive'):
+        with self.subTest("test receive"):
             self._set_receive()
             self.node_model.objects.all().delete()
-            data = self._load('static/netjson-1-link.json')
+            data = self._load("static/netjson-1-link.json")
             response = self.client.post(
-                self.receive_url, data, content_type='text/plain'
+                self.receive_url, data, content_type="text/plain"
             )
             self.assertEqual(response.status_code, 200)
-            self.assertEqual(response.data['detail'], 'data received successfully')
+            self.assertEqual(response.data["detail"], "data received successfully")
             self.assertEqual(self.node_model.objects.count(), 2)
             self.assertEqual(self.link_model.objects.count(), 1)
 
-        with self.subTest('test history'):
+        with self.subTest("test history"):
             response = self.client.get(self.snapshot_url)
             self.assertEqual(response.status_code, 200)
-            self.assertEqual(response.data['type'], 'NetworkGraph')
+            self.assertEqual(response.data["type"], "NetworkGraph")
 
-    @patch.object(APIView, 'get_permissions', return_value=[])
-    @patch.object(APIView, 'get_authenticators', return_value=[])
+    @patch.object(APIView, "get_permissions", return_value=[])
+    @patch.object(APIView, "get_authenticators", return_value=[])
     def test_api_with_auth_disabled(self, perm_mocked, auth_mocked):
-        user = self._get_user(username='tester')
+        user = self._get_user(username="tester")
         self.client.logout()
         self._successful_api_tests()
         self.client.force_login(user)
 
     def test_superuser_with_api_auth_enabled(self):
-        user = self._create_admin(username='superapi', email='superapi@email.com')
+        user = self._create_admin(username="superapi", email="superapi@email.com")
         self.client.force_login(user)
         self._successful_api_tests()
 
-    @patch.object(APIView, 'get_permissions', return_value=[])
-    @patch.object(APIView, 'get_authenticators', return_value=[])
+    @patch.object(APIView, "get_permissions", return_value=[])
+    @patch.object(APIView, "get_authenticators", return_value=[])
     def test_superuser_with_api_auth_disabled(self, perm_mocked, auth_mocked):
-        user = self._create_admin(username='superapi', email='superapi@email.com')
+        user = self._create_admin(username="superapi", email="superapi@email.com")
         self.client.force_login(user)
         self._successful_api_tests()
 
     def test_fetch_topology_create_api(self):
-        path = reverse('network_collection')
+        path = reverse("network_collection")
         data = {
-            'label': 'test-fetch-topology',
-            'organization': self._get_org().id,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'fetch',
-            'url': 'http://127.0.0.1:9090',
-            'published': True,
+            "label": "test-fetch-topology",
+            "organization": self._get_org().id,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "fetch",
+            "url": "http://127.0.0.1:9090",
+            "published": True,
         }
         with self.assertNumQueries(12):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 201)
-        self.assertEqual(response.data['label'], 'test-fetch-topology')
-        self.assertEqual(response.data['parser'], 'netdiff.OlsrParser')
+        self.assertEqual(response.data["label"], "test-fetch-topology")
+        self.assertEqual(response.data["parser"], "netdiff.OlsrParser")
 
     def test_receive_topology_create_api(self):
-        path = reverse('network_collection')
+        path = reverse("network_collection")
         data = {
-            'label': 'test-receive-topology',
-            'organization': self._get_org().pk,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'receive',
-            'key': 'A3DJ62jhd49',
-            'expiration_time': 360,
-            'published': True,
+            "label": "test-receive-topology",
+            "organization": self._get_org().pk,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "receive",
+            "key": "A3DJ62jhd49",
+            "expiration_time": 360,
+            "published": True,
         }
         with self.assertNumQueries(12):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 201)
-        self.assertEqual(response.data['label'], 'test-receive-topology')
-        self.assertEqual(response.data['parser'], 'netdiff.OlsrParser')
-        self.assertEqual(response.data['key'], 'A3DJ62jhd49')
+        self.assertEqual(response.data["label"], "test-receive-topology")
+        self.assertEqual(response.data["parser"], "netdiff.OlsrParser")
+        self.assertEqual(response.data["key"], "A3DJ62jhd49")
 
     def test_topology_detail_receive_url_api(self):
         org1 = self._get_org()
         topo = self._create_topology(organization=org1)
-        path = reverse('network_graph', args=(topo.pk,))
-        r_path = reverse('receive_topology', args=[topo.pk])
-        receive_url = 'http://testserver{0}?key={1}'.format(r_path, topo.key)
+        path = reverse("network_graph", args=(topo.pk,))
+        r_path = reverse("receive_topology", args=[topo.pk])
+        receive_url = "http://testserver{0}?key={1}".format(r_path, topo.key)
         with self.assertNumQueries(7):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['receive_url'], receive_url)
+        self.assertEqual(response.data["receive_url"], receive_url)
 
     def test_topology_receive_no_key_create_api(self):
-        path = reverse('network_collection')
+        path = reverse("network_collection")
         data = {
-            'label': 'test-receive-topology',
-            'organization': self._get_org().pk,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'receive',
-            'key': '',
-            'expiration_time': 360,
-            'published': True,
+            "label": "test-receive-topology",
+            "organization": self._get_org().pk,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "receive",
+            "key": "",
+            "expiration_time": 360,
+            "published": True,
         }
         with self.assertNumQueries(7):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 400)
         self.assertIn(
-            'a key must be specified when using RECEIVE strategy', str(response.content)
+            "a key must be specified when using RECEIVE strategy", str(response.content)
         )
 
     def test_get_topology_detail_api(self):
         org1 = self._get_org()
         topo = self._create_topology(organization=org1)
-        path = reverse('network_graph', args=(topo.pk,))
+        path = reverse("network_graph", args=(topo.pk,))
         with self.assertNumQueries(7):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
 
     def test_get_topology_detail_with_link_api(self):
-        path = reverse('network_graph', args=(self.topology.pk,))
+        path = reverse("network_graph", args=(self.topology.pk,))
         with self.assertNumQueries(7):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertNotEqual(response.data['links'], [])
+        self.assertNotEqual(response.data["links"], [])
 
     def test_put_topology_detail_api(self):
-        path = reverse('network_graph', args=[self.topology.pk])
+        path = reverse("network_graph", args=[self.topology.pk])
         data = {
-            'label': 'ChangeTestNetwork',
-            'organization': self._get_org().pk,
-            'parser': 'netdiff.OlsrParser',
+            "label": "ChangeTestNetwork",
+            "organization": self._get_org().pk,
+            "parser": "netdiff.OlsrParser",
         }
         with self.assertNumQueries(12):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.topology.refresh_from_db()
-        self.assertEqual(self.topology.label, 'ChangeTestNetwork')
+        self.assertEqual(self.topology.label, "ChangeTestNetwork")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['label'], 'ChangeTestNetwork')
-        self.assertEqual(response.data['type'], 'NetworkGraph')
+        self.assertEqual(response.data["label"], "ChangeTestNetwork")
+        self.assertEqual(response.data["type"], "NetworkGraph")
 
     def test_change_strategy_fetch_api_400(self):
         org1 = self._get_org()
         topo = self._create_topology(organization=org1)
-        path = reverse('network_graph', args=(topo.pk,))
+        path = reverse("network_graph", args=(topo.pk,))
         data = {
-            'label': 'ChangeTestNetwork',
-            'organization': org1.pk,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'fetch',
-            'url': '',
+            "label": "ChangeTestNetwork",
+            "organization": org1.pk,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "fetch",
+            "url": "",
         }
         with self.assertNumQueries(6):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 400)
         self.assertIn(
-            'An url must be specified when using FETCH strategy', str(response.content)
+            "An url must be specified when using FETCH strategy", str(response.content)
         )
 
     def test_change_strategy_receive_api_400(self):
         org1 = self._get_org()
         topo = self._create_topology(organization=org1)
-        path = reverse('network_graph', args=(topo.pk,))
+        path = reverse("network_graph", args=(topo.pk,))
         data = {
-            'label': 'ChangeTestNetwork',
-            'organization': self._get_org().pk,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'receive',
-            'key': '',
+            "label": "ChangeTestNetwork",
+            "organization": self._get_org().pk,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "receive",
+            "key": "",
         }
         with self.assertNumQueries(6):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 400)
         self.assertIn(
-            'A key must be specified when using RECEIVE strategy', str(response.content)
+            "A key must be specified when using RECEIVE strategy", str(response.content)
         )
 
     def test_change_strategy_fetch_api_200(self):
         org1 = self._get_org()
-        topo = self._create_topology(organization=org1, strategy='receive')
-        path = reverse('network_graph', args=[topo.pk])
-        self.assertEqual(topo.strategy, 'receive')
+        topo = self._create_topology(organization=org1, strategy="receive")
+        path = reverse("network_graph", args=[topo.pk])
+        self.assertEqual(topo.strategy, "receive")
         data = {
-            'label': 'ChangeTestNetwork',
-            'organization': org1.pk,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'fetch',
-            'url': 'http://127.0.0.1:9090',
+            "label": "ChangeTestNetwork",
+            "organization": org1.pk,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "fetch",
+            "url": "http://127.0.0.1:9090",
         }
         with self.assertNumQueries(12):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['strategy'], 'fetch')
+        self.assertEqual(response.data["strategy"], "fetch")
         topo.refresh_from_db()
-        self.assertEqual(topo.strategy, 'fetch')
+        self.assertEqual(topo.strategy, "fetch")
 
     def test_change_strategy_receive_api_200(self):
         org1 = self._get_org()
-        topo = self._create_topology(organization=org1, strategy='fetch')
-        path = reverse('network_graph', args=[topo.pk])
-        self.assertEqual(topo.strategy, 'fetch')
+        topo = self._create_topology(organization=org1, strategy="fetch")
+        path = reverse("network_graph", args=[topo.pk])
+        self.assertEqual(topo.strategy, "fetch")
         data = {
-            'label': 'ChangeTestNetwork',
-            'organization': org1.pk,
-            'parser': 'netdiff.OlsrParser',
-            'strategy': 'receive',
-            'key': 12345,
+            "label": "ChangeTestNetwork",
+            "organization": org1.pk,
+            "parser": "netdiff.OlsrParser",
+            "strategy": "receive",
+            "key": 12345,
         }
         with self.assertNumQueries(12):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['strategy'], 'receive')
+        self.assertEqual(response.data["strategy"], "receive")
         topo.refresh_from_db()
-        self.assertEqual(topo.strategy, 'receive')
+        self.assertEqual(topo.strategy, "receive")
 
     def test_patch_topology_detail_api(self):
-        path = reverse('network_graph', args=(self.topology.pk,))
+        path = reverse("network_graph", args=(self.topology.pk,))
         data = {
-            'label': 'ChangeTestNetwork',
+            "label": "ChangeTestNetwork",
         }
         with self.assertNumQueries(11):
-            response = self.client.patch(path, data, content_type='application/json')
+            response = self.client.patch(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['label'], 'ChangeTestNetwork')
+        self.assertEqual(response.data["label"], "ChangeTestNetwork")
 
     def test_delete_topology_api(self):
-        path = reverse('network_graph', args=(self.topology.pk,))
+        path = reverse("network_graph", args=(self.topology.pk,))
         response = self.client.delete(path)
         self.assertEqual(response.status_code, 204)
 
     def test_topology_filter_by_org_api(self):
-        org1 = self._create_org(name='org1')
-        org2 = self._create_org(name='org2')
-        topo1 = self._create_topology(label='topo1', organization=org1)
-        topo2 = self._create_topology(label='topo2', organization=org2)
-        user1 = self._create_user(username='test-filter', email='test@filter.com')
+        org1 = self._create_org(name="org1")
+        org2 = self._create_org(name="org2")
+        topo1 = self._create_topology(label="topo1", organization=org1)
+        topo2 = self._create_topology(label="topo2", organization=org2)
+        user1 = self._create_user(username="test-filter", email="test@filter.com")
         self._create_org_user(user=user1, organization=org1, is_admin=True)
-        view_perm = Permission.objects.filter(codename='view_topology')
+        view_perm = Permission.objects.filter(codename="view_topology")
         user1.user_permissions.add(*view_perm)
         self.client.force_login(user1)
-        with self.subTest('test network collection view'):
-            path = reverse('network_collection')
+        with self.subTest("test network collection view"):
+            path = reverse("network_collection")
             with self.assertNumQueries(7):
                 response = self.client.get(path)
             self.assertEqual(response.status_code, 200)
             self.assertIn(str(topo1.id), str(response.content))
             self.assertNotIn(str(topo2.id), str(response.content))
 
-        with self.subTest('test network graph view'):
+        with self.subTest("test network graph view"):
             # Get the topology graph view of member org 200
-            path = reverse('network_graph', args=(topo1.pk,))
+            path = reverse("network_graph", args=(topo1.pk,))
             with self.assertNumQueries(7):
                 response = self.client.get(path)
             self.assertEqual(response.status_code, 200)
-            self.assertEqual(response.data['id'], str(topo1.id))
+            self.assertEqual(response.data["id"], str(topo1.id))
 
             # Get the topology graph view of different org 404
-            path = reverse('network_graph', args=(topo2.pk,))
+            path = reverse("network_graph", args=(topo2.pk,))
             with self.assertNumQueries(5):
                 response = self.client.get(path)
             self.assertEqual(response.status_code, 404)
 
     def test_topology_filter_fields_by_org_api(self):
         org1 = self._get_org()
-        user1 = self._create_user(username='test-filter', email='test@filter.com')
+        user1 = self._create_user(username="test-filter", email="test@filter.com")
         self._create_org_user(user=user1, organization=org1, is_admin=True)
-        topo_perm = Permission.objects.filter(codename__endswith='topology')
+        topo_perm = Permission.objects.filter(codename__endswith="topology")
         user1.user_permissions.add(*topo_perm)
         self.client.force_login(user1)
-        with self.subTest('test network collection view'):
-            path = reverse('network_collection')
+        with self.subTest("test network collection view"):
+            path = reverse("network_collection")
             with self.assertNumQueries(8):
-                response = self.client.get(path, {'format': 'api'})
+                response = self.client.get(path, {"format": "api"})
             self.assertEqual(response.status_code, 200)
             self.assertEqual(Organization.objects.count(), 2)
-            self.assertContains(response, 'test org</option>')
-            self.assertNotContains(response, 'default</option>')
+            self.assertContains(response, "test org</option>")
+            self.assertNotContains(response, "default</option>")
 
-        with self.subTest('test network graph view'):
-            topo1 = self._create_topology(label='topo1', organization=org1)
-            path = reverse('network_graph', args=(topo1.pk,))
+        with self.subTest("test network graph view"):
+            topo1 = self._create_topology(label="topo1", organization=org1)
+            path = reverse("network_graph", args=(topo1.pk,))
             with self.assertNumQueries(14):
-                response = self.client.get(path, {'format': 'api'})
+                response = self.client.get(path, {"format": "api"})
             self.assertEqual(response.status_code, 200)
             self.assertEqual(Organization.objects.count(), 2)
-            self.assertContains(response, 'test org</option>')
-            self.assertNotContains(response, 'default</option>')
+            self.assertContains(response, "test org</option>")
+            self.assertNotContains(response, "default</option>")
 
     def test_node_list_api(self):
-        path = reverse('node_list')
+        path = reverse("node_list")
         with self.assertNumQueries(6):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['count'], 2)
+        self.assertEqual(response.data["count"], 2)
 
     def test_node_list_multitenancy(self):
-        path = reverse('node_list')
-        org2 = self._create_org(name='org2')
+        path = reverse("node_list")
+        org2 = self._create_org(name="org2")
         t2 = self._create_topology(organization=org2)
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t2, organization=org2
+            label="node2", addresses=["192.168.0.2"], topology=t2, organization=org2
         )
         self.assertEqual(Node.objects.count(), 3)
         with self.assertNumQueries(6):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
         # Only nodes related to user's organization are returned
-        self.assertEqual(response.data['count'], 2)
+        self.assertEqual(response.data["count"], 2)
 
     def test_node_list_filter(self):
         admin = self._get_admin()
         self.client.force_login(admin)
         org1 = self._get_org()
-        org2 = self._create_org(name='org2')
+        org2 = self._create_org(name="org2")
         t2 = self._create_topology(organization=org2)
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t2, organization=org2
+            label="node2", addresses=["192.168.0.2"], topology=t2, organization=org2
         )
-        path = reverse('node_list')
+        path = reverse("node_list")
 
-        with self.subTest('Test list without filters'):
+        with self.subTest("Test list without filters"):
             response = self.client.get(path)
-            self.assertEqual(response.data['count'], 3)
+            self.assertEqual(response.data["count"], 3)
 
-        with self.subTest('Test filter by organization'):
-            response = self.client.get(f'{path}?organization={org1.pk}')
-            self.assertEqual(response.data['count'], 2)
+        with self.subTest("Test filter by organization"):
+            response = self.client.get(f"{path}?organization={org1.pk}")
+            self.assertEqual(response.data["count"], 2)
 
-        with self.subTest('Test filter by organization slug'):
-            response = self.client.get(f'{path}?organization_slug={org1.slug}')
-            self.assertEqual(response.data['count'], 2)
+        with self.subTest("Test filter by organization slug"):
+            response = self.client.get(f"{path}?organization_slug={org1.slug}")
+            self.assertEqual(response.data["count"], 2)
 
-        with self.subTest('Test filter by topology'):
-            response = self.client.get(f'{path}?topology={t2.pk}')
-            self.assertEqual(response.data['count'], 1)
+        with self.subTest("Test filter by topology"):
+            response = self.client.get(f"{path}?topology={t2.pk}")
+            self.assertEqual(response.data["count"], 1)
 
     def test_node_create_api(self):
-        path = reverse('node_list')
+        path = reverse("node_list")
         data = {
-            'topology': self.topology.pk,
-            'label': 'test-node',
-            'addresses': ['192.168.0.1'],
-            'properties': {},
-            'user_properties': {},
+            "topology": self.topology.pk,
+            "label": "test-node",
+            "addresses": ["192.168.0.1"],
+            "properties": {},
+            "user_properties": {},
         }
         with self.assertNumQueries(13):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 201)
-        self.assertEqual(response.data['topology'], self.topology.pk)
-        self.assertEqual(response.data['label'], 'test-node')
-        self.assertEqual(response.data['addresses'], ['192.168.0.1'])
+        self.assertEqual(response.data["topology"], self.topology.pk)
+        self.assertEqual(response.data["label"], "test-node")
+        self.assertEqual(response.data["addresses"], ["192.168.0.1"])
 
     def test_node_create_api_shared_topology(self):
         admin = self._get_admin()
@@ -734,197 +734,197 @@ def test_node_create_api_shared_topology(self):
         topology = self._create_topology(organization=None)
         org = self._get_org()
         data = {
-            'topology': topology.pk,
-            'label': 'test-node',
-            'addresses': ['192.168.0.1'],
-            'properties': {},
-            'user_properties': {},
-            'organization': org.pk,
+            "topology": topology.pk,
+            "label": "test-node",
+            "addresses": ["192.168.0.1"],
+            "properties": {},
+            "user_properties": {},
+            "organization": org.pk,
         }
-        path = reverse('node_list')
+        path = reverse("node_list")
         with self.assertNumQueries(11):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 201)
-        self.assertEqual(response.data['topology'], topology.pk)
-        self.assertEqual(response.data['organization'], org.pk)
+        self.assertEqual(response.data["topology"], topology.pk)
+        self.assertEqual(response.data["organization"], org.pk)
 
     def test_node_detail_api(self):
-        path = reverse('node_detail', args=(self.node1.pk,))
+        path = reverse("node_detail", args=(self.node1.pk,))
         with self.assertNumQueries(6):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['id'], str(self.node1.pk))
-        self.assertEqual(response.data['label'], self.node1.label)
-        self.assertEqual(response.data['topology'], self.node1.topology.pk)
-        self.assertEqual(response.data['organization'], self.node1.organization.pk)
-        self.assertEqual(response.data['addresses'], self.node1.addresses)
-        self.assertEqual(response.data['properties'], self.node1.properties)
-        self.assertEqual(response.data['user_properties'], self.node1.user_properties)
-        self.assertIn('created', response.data)
-        self.assertIn('modified', response.data)
+        self.assertEqual(response.data["id"], str(self.node1.pk))
+        self.assertEqual(response.data["label"], self.node1.label)
+        self.assertEqual(response.data["topology"], self.node1.topology.pk)
+        self.assertEqual(response.data["organization"], self.node1.organization.pk)
+        self.assertEqual(response.data["addresses"], self.node1.addresses)
+        self.assertEqual(response.data["properties"], self.node1.properties)
+        self.assertEqual(response.data["user_properties"], self.node1.user_properties)
+        self.assertIn("created", response.data)
+        self.assertIn("modified", response.data)
 
     def test_node_put_api(self):
         data = {
-            'topology': self.topology.pk,
-            'label': 'change-node',
-            'addresses': ['192.168.0.1', '192.168.0.2'],
-            'properties': {},
-            'user_properties': {},
+            "topology": self.topology.pk,
+            "label": "change-node",
+            "addresses": ["192.168.0.1", "192.168.0.2"],
+            "properties": {},
+            "user_properties": {},
         }
-        path = reverse('node_detail', args=(self.node1.pk,))
+        path = reverse("node_detail", args=(self.node1.pk,))
         with self.assertNumQueries(13):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['label'], 'change-node')
-        self.assertEqual(response.data['addresses'], ['192.168.0.1', '192.168.0.2'])
+        self.assertEqual(response.data["label"], "change-node")
+        self.assertEqual(response.data["addresses"], ["192.168.0.1", "192.168.0.2"])
 
     def test_node_patch_api(self):
-        path = reverse('node_detail', args=(self.node1.pk,))
-        data = {'label': 'change-node'}
+        path = reverse("node_detail", args=(self.node1.pk,))
+        data = {"label": "change-node"}
         with self.assertNumQueries(12):
-            response = self.client.patch(path, data, content_type='application/json')
+            response = self.client.patch(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['label'], 'change-node')
+        self.assertEqual(response.data["label"], "change-node")
 
     def test_node_delete_api(self):
         node = self._create_node(
-            label='delete-node', addresses=['192.168.0.1'], topology=self.topology
+            label="delete-node", addresses=["192.168.0.1"], topology=self.topology
         )
-        path = reverse('node_detail', args=(node.pk,))
+        path = reverse("node_detail", args=(node.pk,))
         response = self.client.delete(path)
         self.assertEqual(response.status_code, 204)
-        self.assertEqual(Node.objects.filter(label='delete-node').count(), 0)
+        self.assertEqual(Node.objects.filter(label="delete-node").count(), 0)
 
     def test_link_list_api(self):
-        path = reverse('link_list')
+        path = reverse("link_list")
         with self.assertNumQueries(6):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['count'], 1)
+        self.assertEqual(response.data["count"], 1)
 
     def test_link_list_filters(self):
         admin = self._get_admin()
         self.client.force_login(admin)
         org1 = self._get_org()
-        org2 = self._create_org(name='org2')
+        org2 = self._create_org(name="org2")
         t2 = self._create_topology(organization=org2)
         node1 = self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t2, organization=org2
+            label="node2", addresses=["192.168.0.2"], topology=t2, organization=org2
         )
         node2 = self._create_node(
-            label='node2', addresses=['192.168.0.3'], topology=t2, organization=org2
+            label="node2", addresses=["192.168.0.3"], topology=t2, organization=org2
         )
-        self._create_link(source=node1, target=node2, topology=t2, status='down')
-        path = reverse('link_list')
+        self._create_link(source=node1, target=node2, topology=t2, status="down")
+        path = reverse("link_list")
 
-        with self.subTest('Test list without filters'):
+        with self.subTest("Test list without filters"):
             response = self.client.get(path)
-            self.assertEqual(response.data['count'], 2)
+            self.assertEqual(response.data["count"], 2)
 
-        with self.subTest('Test filter by organization'):
-            response = self.client.get(f'{path}?organization={org1.pk}')
-            self.assertEqual(response.data['count'], 1)
+        with self.subTest("Test filter by organization"):
+            response = self.client.get(f"{path}?organization={org1.pk}")
+            self.assertEqual(response.data["count"], 1)
 
-        with self.subTest('Test filter by organization slug'):
-            response = self.client.get(f'{path}?organization_slug={org1.slug}')
-            self.assertEqual(response.data['count'], 1)
+        with self.subTest("Test filter by organization slug"):
+            response = self.client.get(f"{path}?organization_slug={org1.slug}")
+            self.assertEqual(response.data["count"], 1)
 
-        with self.subTest('Test filter by topology'):
-            response = self.client.get(f'{path}?topology={t2.pk}')
-            self.assertEqual(response.data['count'], 1)
+        with self.subTest("Test filter by topology"):
+            response = self.client.get(f"{path}?topology={t2.pk}")
+            self.assertEqual(response.data["count"], 1)
 
-        with self.subTest('Test filter by status'):
-            response = self.client.get(f'{path}?status=down')
-            self.assertEqual(response.data['count'], 1)
+        with self.subTest("Test filter by status"):
+            response = self.client.get(f"{path}?status=down")
+            self.assertEqual(response.data["count"], 1)
 
     def test_link_create_api(self):
-        path = reverse('link_list')
-        node3 = self._create_node(label='node3', topology=self.topology)
+        path = reverse("link_list")
+        node3 = self._create_node(label="node3", topology=self.topology)
         data = {
-            'topology': self.topology.pk,
-            'source': self.node1.pk,
-            'target': node3.pk,
-            'cost': 1.0,
-            'properties': {},
-            'user_properties': {},
+            "topology": self.topology.pk,
+            "source": self.node1.pk,
+            "target": node3.pk,
+            "cost": 1.0,
+            "properties": {},
+            "user_properties": {},
         }
         with self.assertNumQueries(16):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 201)
-        self.assertEqual(response.data['topology'], self.topology.pk)
-        self.assertEqual(response.data['status'], 'up')
-        self.assertEqual(response.data['source'], self.node1.pk)
-        self.assertEqual(response.data['target'], node3.pk)
+        self.assertEqual(response.data["topology"], self.topology.pk)
+        self.assertEqual(response.data["status"], "up")
+        self.assertEqual(response.data["source"], self.node1.pk)
+        self.assertEqual(response.data["target"], node3.pk)
 
     def test_link_create_with_wrong_value_format_api(self):
-        path = reverse('link_list')
-        node3 = self._create_node(label='node3', topology=self.topology)
+        path = reverse("link_list")
+        node3 = self._create_node(label="node3", topology=self.topology)
         data = {
-            'topology': self.topology.pk,
-            'source': self.node1.pk,
-            'target': node3.pk,
-            'cost': 1.0,
-            'properties': 0,
-            'user_properties': 122343,
+            "topology": self.topology.pk,
+            "source": self.node1.pk,
+            "target": node3.pk,
+            "cost": 1.0,
+            "properties": 0,
+            "user_properties": 122343,
         }
         with self.assertNumQueries(7):
-            response = self.client.post(path, data, content_type='application/json')
+            response = self.client.post(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 400)
         self.assertEqual(
-            response.data['properties'][0].title(),
-            'Value Must Be Valid Json Or Key, Valued Pair.',
+            response.data["properties"][0].title(),
+            "Value Must Be Valid Json Or Key, Valued Pair.",
         )
         self.assertEqual(
-            response.data['user_properties'][0].title(),
-            'Value Must Be Valid Json Or Key, Valued Pair.',
+            response.data["user_properties"][0].title(),
+            "Value Must Be Valid Json Or Key, Valued Pair.",
         )
 
     def test_link_detail_api(self):
-        path = reverse('link_detail', args=(self.link.pk,))
+        path = reverse("link_detail", args=(self.link.pk,))
         with self.assertNumQueries(6):
             response = self.client.get(path)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['id'], str(self.link.pk))
-        self.assertEqual(response.data['topology'], self.topology.pk)
-        self.assertEqual(response.data['source'], self.node1.pk)
-        self.assertEqual(response.data['target'], self.node2.pk)
-        self.assertEqual(response.data['organization'], self.link.organization.pk)
-        self.assertEqual(response.data['status'], self.link.status)
-        self.assertEqual(response.data['cost'], self.link.cost)
-        self.assertEqual(response.data['cost_text'], self.link.cost_text)
-        self.assertEqual(response.data['properties'], self.link.properties)
-        self.assertEqual(response.data['user_properties'], self.link.user_properties)
-        self.assertIn('created', response.data)
-        self.assertIn('modified', response.data)
+        self.assertEqual(response.data["id"], str(self.link.pk))
+        self.assertEqual(response.data["topology"], self.topology.pk)
+        self.assertEqual(response.data["source"], self.node1.pk)
+        self.assertEqual(response.data["target"], self.node2.pk)
+        self.assertEqual(response.data["organization"], self.link.organization.pk)
+        self.assertEqual(response.data["status"], self.link.status)
+        self.assertEqual(response.data["cost"], self.link.cost)
+        self.assertEqual(response.data["cost_text"], self.link.cost_text)
+        self.assertEqual(response.data["properties"], self.link.properties)
+        self.assertEqual(response.data["user_properties"], self.link.user_properties)
+        self.assertIn("created", response.data)
+        self.assertIn("modified", response.data)
 
     def test_link_put_api(self):
-        path = reverse('link_detail', args=(self.link.pk,))
+        path = reverse("link_detail", args=(self.link.pk,))
         data = {
-            'topology': self.topology.pk,
-            'source': self.node1.pk,
-            'target': self.node2.pk,
-            'cost': 21.0,
-            'properties': {},
-            'user_properties': {'user': 'tester'},
+            "topology": self.topology.pk,
+            "source": self.node1.pk,
+            "target": self.node2.pk,
+            "cost": 21.0,
+            "properties": {},
+            "user_properties": {"user": "tester"},
         }
         with self.assertNumQueries(16):
-            response = self.client.put(path, data, content_type='application/json')
+            response = self.client.put(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['cost'], 21.0)
-        self.assertEqual(response.data['properties'], {})
-        self.assertEqual(response.data['user_properties'], {'user': 'tester'})
+        self.assertEqual(response.data["cost"], 21.0)
+        self.assertEqual(response.data["properties"], {})
+        self.assertEqual(response.data["user_properties"], {"user": "tester"})
 
     def test_link_patch_api(self):
-        path = reverse('link_detail', args=(self.link.pk,))
-        data = {'cost': 50.0}
+        path = reverse("link_detail", args=(self.link.pk,))
+        data = {"cost": 50.0}
         with self.assertNumQueries(13):
-            response = self.client.patch(path, data, content_type='application/json')
+            response = self.client.patch(path, data, content_type="application/json")
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['cost'], 50.0)
+        self.assertEqual(response.data["cost"], 50.0)
 
     def test_link_delete_api(self):
         self.assertEqual(Link.objects.count(), 1)
-        path = reverse('link_detail', args=(self.link.pk,))
+        path = reverse("link_detail", args=(self.link.pk,))
         response = self.client.delete(path)
         self.assertEqual(response.status_code, 204)
         self.assertEqual(Link.objects.count(), 0)
diff --git a/openwisp_network_topology/tests/test_link.py b/openwisp_network_topology/tests/test_link.py
index a18ac057..ceef3b37 100644
--- a/openwisp_network_topology/tests/test_link.py
+++ b/openwisp_network_topology/tests/test_link.py
@@ -8,9 +8,9 @@
 from ..utils import link_status_changed
 from .utils import CreateGraphObjectsMixin
 
-Link = swapper.load_model('topology', 'Link')
-Node = swapper.load_model('topology', 'Node')
-Topology = swapper.load_model('topology', 'Topology')
+Link = swapper.load_model("topology", "Link")
+Node = swapper.load_model("topology", "Node")
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TestLink(TestOrganizationMixin, CreateGraphObjectsMixin, TestCase):
@@ -22,10 +22,10 @@ def setUp(self):
         org = self._create_org()
         t = self._create_topology(organization=org)
         self._create_node(
-            label='node1', addresses=['192.168.0.1'], topology=t, organization=org
+            label="node1", addresses=["192.168.0.1"], topology=t, organization=org
         )
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t, organization=org
+            label="node2", addresses=["192.168.0.2"], topology=t, organization=org
         )
 
     def _get_nodes(self):
@@ -48,7 +48,7 @@ def test_clean_properties_status(self):
         t = self.topology_model.objects.first()
         node1, node2 = self._get_nodes()
         link = t._create_link(
-            source=node1, target=node2, cost=1.0, properties={'status': 'up'}
+            source=node1, target=node2, cost=1.0, properties={"status": "up"}
         )
         link.full_clean()
         # status must not be saved in properties or it will override the real status
@@ -75,40 +75,40 @@ def test_json(self):
             source=node1,
             target=node2,
             cost=1.0,
-            cost_text='100mbit/s',
+            cost_text="100mbit/s",
             properties={"pretty": True},
         )
         self.assertEqual(
             dict(link.json(dict=True)),
             {
-                'source': '192.168.0.1',
-                'target': '192.168.0.2',
-                'cost': 1.0,
-                'cost_text': '100mbit/s',
-                'properties': {
-                    'pretty': True,
-                    'status': 'up',
-                    'created': link.created,
-                    'modified': link.modified,
-                    'status_changed': link.status_changed,
+                "source": "192.168.0.1",
+                "target": "192.168.0.2",
+                "cost": 1.0,
+                "cost_text": "100mbit/s",
+                "properties": {
+                    "pretty": True,
+                    "status": "up",
+                    "created": link.created,
+                    "modified": link.modified,
+                    "status_changed": link.status_changed,
                 },
             },
         )
         self.assertIsInstance(link.json(), str)
-        link.status = 'down'
+        link.status = "down"
         link.save()
         link.refresh_from_db()
         netjson = link.json(dict=True)
-        with self.subTest('status should not be saved in properties'):
-            self.assertNotIn('status', link.properties)
-        with self.subTest('status should not be overridden'):
-            self.assertEqual(netjson['properties']['status'], 'down')
-        with self.subTest('testing original=True'):
+        with self.subTest("status should not be saved in properties"):
+            self.assertNotIn("status", link.properties)
+        with self.subTest("status should not be overridden"):
+            self.assertEqual(netjson["properties"]["status"], "down")
+        with self.subTest("testing original=True"):
             netjson = link.json(dict=True, original=True)
-            self.assertNotIn('status', netjson['properties'])
-            self.assertNotIn('status_changed', netjson['properties'])
-            self.assertNotIn('created', netjson['properties'])
-            self.assertNotIn('modified', netjson['properties'])
+            self.assertNotIn("status", netjson["properties"])
+            self.assertNotIn("status_changed", netjson["properties"])
+            self.assertNotIn("created", netjson["properties"])
+            self.assertNotIn("modified", netjson["properties"])
 
     def test_get_from_nodes(self):
         t = self.topology_model.objects.first()
@@ -117,14 +117,14 @@ def test_get_from_nodes(self):
             source=node1,
             target=node2,
             cost=1.0,
-            cost_text='100mbit/s',
+            cost_text="100mbit/s",
             properties='{"pretty": true}',
         )
         link.full_clean()
         link.save()
-        link = self.link_model.get_from_nodes('192.168.0.1', '192.168.0.2', t)
+        link = self.link_model.get_from_nodes("192.168.0.1", "192.168.0.2", t)
         self.assertIsInstance(link, self.link_model)
-        link = self.link_model.get_from_nodes('wrong', 'wrong', t)
+        link = self.link_model.get_from_nodes("wrong", "wrong", t)
         self.assertIsNone(link)
 
     def test_status_change_signal_sent(self):
@@ -132,77 +132,77 @@ def test_status_change_signal_sent(self):
         t = self.topology_model.objects.first()
         node1, node2 = self._get_nodes()
         with catch_signal(link_status_changed) as handler:
-            link = t._create_link(source=node1, target=node2, cost=1.0, status='up')
+            link = t._create_link(source=node1, target=node2, cost=1.0, status="up")
             link.save()
             handler.assert_not_called()
         with catch_signal(link_status_changed) as handler:
-            link.status = 'down'
+            link.status = "down"
             link.save()
         handler.assert_called_once_with(
             link=link, sender=self.link_model, signal=link_status_changed
         )
-        self.assertEqual(link.status, 'down')
+        self.assertEqual(link.status, "down")
 
     def test_validate_organization(self):
         org1 = self._get_org()
         org1_topology = self.topology_model.objects.first()
         org1_node1, org1_node2 = self._get_nodes()
-        shared_topology = self._create_topology(label='shared', organization=None)
-        org2 = self._create_org(name='org2')
+        shared_topology = self._create_topology(label="shared", organization=None)
+        org2 = self._create_org(name="org2")
         org2_node1 = self._create_node(
-            label='org2_node1',
-            addresses=['192.168.0.3'],
+            label="org2_node1",
+            addresses=["192.168.0.3"],
             topology=shared_topology,
             organization=org2,
         )
 
-        with self.subTest('Test toplogy and nodes belongs to different organizations'):
+        with self.subTest("Test toplogy and nodes belongs to different organizations"):
             # Test source node
             link = self.link_model(
                 source=org2_node1,
                 target=org2_node1,
                 cost=1.0,
-                cost_text='100mbit/s',
+                cost_text="100mbit/s",
                 topology=org1_topology,
             )
             with self.assertRaises(ValidationError) as context_manager:
                 link.full_clean()
             source_expected_error = (
-                'Source node and topology should have same organization.'
+                "Source node and topology should have same organization."
             )
             target_expected_error = (
-                'Target node and topology should have same organization.'
+                "Target node and topology should have same organization."
             )
             self.assertIn(
-                source_expected_error, context_manager.exception.message_dict['source']
+                source_expected_error, context_manager.exception.message_dict["source"]
             )
             self.assertIn(
-                target_expected_error, context_manager.exception.message_dict['target']
+                target_expected_error, context_manager.exception.message_dict["target"]
             )
 
-        with self.subTest('Test link gets organization of non-shared topology'):
+        with self.subTest("Test link gets organization of non-shared topology"):
             link = self.link_model(
                 source=org1_node1,
                 target=org1_node2,
                 cost=1.0,
-                cost_text='100mbit/s',
+                cost_text="100mbit/s",
                 topology=org1_topology,
             )
             link.full_clean()
             self.assertEqual(link.organization, org1_topology.organization)
 
-        with self.subTest('Test non-shared link of shared topology'):
+        with self.subTest("Test non-shared link of shared topology"):
             # Since source and target nodes belong to the same organization,
             # link will get organization of the nodes
             source_node = self._create_node(
-                label='org1_node1_shared_topology',
-                addresses=['10.0.0.1'],
+                label="org1_node1_shared_topology",
+                addresses=["10.0.0.1"],
                 topology=shared_topology,
                 organization=org1,
             )
             target_node = self._create_node(
-                label='org1_node2_shared_topology',
-                addresses=['10.0.0.2'],
+                label="org1_node2_shared_topology",
+                addresses=["10.0.0.2"],
                 topology=shared_topology,
                 organization=org1,
             )
@@ -210,24 +210,24 @@ def test_validate_organization(self):
                 source=source_node,
                 target=target_node,
                 cost=1.0,
-                cost_text='100mbit/s',
+                cost_text="100mbit/s",
                 topology=shared_topology,
             )
             link.full_clean()
             self.assertEqual(link.organization, org1)
 
-        with self.subTest('Test shared link of shared topology'):
+        with self.subTest("Test shared link of shared topology"):
             # Since source and target nodes belongs to different organizations,
             # link will be shared.
             source_node = self._create_node(
-                label='org1_node1_shared_topology',
-                addresses=['10.0.0.3'],
+                label="org1_node1_shared_topology",
+                addresses=["10.0.0.3"],
                 topology=shared_topology,
                 organization=org1,
             )
             target_node = self._create_node(
-                label='org2_node1_shared_topology',
-                addresses=['10.0.0.4'],
+                label="org2_node1_shared_topology",
+                addresses=["10.0.0.4"],
                 topology=shared_topology,
                 organization=org2,
             )
@@ -235,7 +235,7 @@ def test_validate_organization(self):
                 source=source_node,
                 target=target_node,
                 cost=1.0,
-                cost_text='100mbit/s',
+                cost_text="100mbit/s",
                 topology=shared_topology,
             )
             link.full_clean()
@@ -245,19 +245,19 @@ def test_user_properties_in_json(self):
         t = self.topology_model.objects.first()
         node1, node2 = self._get_nodes()
         link = self.link_model(
-            source=node1, target=node2, cost=1.0, cost_text='100mbit/s', topology=t
+            source=node1, target=node2, cost=1.0, cost_text="100mbit/s", topology=t
         )
-        link.properties = {'wired': True}
-        link.user_properties = {'user_property': True}
+        link.properties = {"wired": True}
+        link.user_properties = {"user_property": True}
         link.full_clean()
         link.save()
 
-        with self.subTest('view json when original is False'):
+        with self.subTest("view json when original is False"):
             data = link.json(dict=True)
-            self.assertIn('wired', data['properties'])
-            self.assertIn('user_property', data['properties'])
+            self.assertIn("wired", data["properties"])
+            self.assertIn("user_property", data["properties"])
 
-        with self.subTest('view json when original is True'):
+        with self.subTest("view json when original is True"):
             data = link.json(dict=True, original=True)
-            self.assertIn('wired', data['properties'])
-            self.assertNotIn('user_property', data['properties'])
+            self.assertIn("wired", data["properties"])
+            self.assertNotIn("user_property", data["properties"])
diff --git a/openwisp_network_topology/tests/test_node.py b/openwisp_network_topology/tests/test_node.py
index b323d6f6..19719e6f 100644
--- a/openwisp_network_topology/tests/test_node.py
+++ b/openwisp_network_topology/tests/test_node.py
@@ -7,8 +7,8 @@
 
 from .utils import CreateGraphObjectsMixin
 
-Node = swapper.load_model('topology', 'Node')
-Topology = swapper.load_model('topology', 'Topology')
+Node = swapper.load_model("topology", "Node")
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TestNode(CreateGraphObjectsMixin, TestOrganizationMixin, TestCase):
@@ -20,20 +20,20 @@ def setUp(self):
         org = self._get_org()
         t = self._create_topology(organization=org)
         self._create_node(
-            label='node1', addresses=['192.168.0.1'], topology=t, organization=org
+            label="node1", addresses=["192.168.0.1"], topology=t, organization=org
         )
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t, organization=org
+            label="node2", addresses=["192.168.0.2"], topology=t, organization=org
         )
 
     def test_str(self):
-        n = self.node_model(addresses=['192.168.0.1'], label='test node')
+        n = self.node_model(addresses=["192.168.0.1"], label="test node")
         self.assertIsInstance(str(n), str)
 
     def test_clean_properties(self):
         t = self.topology_model.objects.first()
         n = t._create_node(
-            addresses=['192.168.0.1'], label='test node', properties=None
+            addresses=["192.168.0.1"], label="test node", properties=None
         )
         n.full_clean()
         self.assertEqual(n.properties, {})
@@ -41,102 +41,102 @@ def test_clean_properties(self):
     def test_node_address_single(self):
         t = self.topology_model.objects.first()
         n = t._create_node(
-            addresses=['192.168.0.1'], label='test node', properties=None
+            addresses=["192.168.0.1"], label="test node", properties=None
         )
         n.full_clean()
         n.save()
-        self.assertEqual(n.addresses[0], '192.168.0.1')
-        self.assertEqual(n.addresses, ['192.168.0.1'])
+        self.assertEqual(n.addresses[0], "192.168.0.1")
+        self.assertEqual(n.addresses, ["192.168.0.1"])
 
     def test_node_address_multiple(self):
         t = self.topology_model.objects.first()
         n = t._create_node(
-            label='test node',
-            addresses=['192.168.0.1', '10.0.0.1', '10.0.0.2', '10.0.0.3'],
+            label="test node",
+            addresses=["192.168.0.1", "10.0.0.1", "10.0.0.2", "10.0.0.3"],
         )
         self.assertEqual(
-            n.addresses, ['192.168.0.1', '10.0.0.1', '10.0.0.2', '10.0.0.3']
+            n.addresses, ["192.168.0.1", "10.0.0.1", "10.0.0.2", "10.0.0.3"]
         )
 
     def test_node_local_addresses(self):
         t = self.topology_model.objects.first()
         n = t._create_node(
-            label='test node', addresses=['192.168.0.1', '10.0.0.1', '10.0.0.2']
+            label="test node", addresses=["192.168.0.1", "10.0.0.1", "10.0.0.2"]
         )
-        self.assertEqual(n.local_addresses, ['10.0.0.1', '10.0.0.2'])
+        self.assertEqual(n.local_addresses, ["10.0.0.1", "10.0.0.2"])
 
     def test_node_name(self):
         t = self.topology_model.objects.first()
-        n = t._create_node(addresses=['192.168.0.1', '10.0.0.1'])
-        self.assertEqual(n.name, '192.168.0.1')
-        n.label = 'test node'
-        self.assertEqual(n.name, 'test node')
+        n = t._create_node(addresses=["192.168.0.1", "10.0.0.1"])
+        self.assertEqual(n.name, "192.168.0.1")
+        n.label = "test node"
+        self.assertEqual(n.name, "test node")
 
     def test_node_without_name(self):
         # According to the RFC, a node MAY not have name nor local_addresses defined
         t = self.topology_model.objects.first()
         n = t._create_node(addresses=[])
-        self.assertEqual(n.name, '')
+        self.assertEqual(n.name, "")
 
     def test_json(self):
         t = self.topology_model.objects.first()
         n = t._create_node(
-            label='test node',
-            addresses=['192.168.0.1', '10.0.0.1'],
+            label="test node",
+            addresses=["192.168.0.1", "10.0.0.1"],
             properties={"gateway": True},
         )
         self.assertEqual(
             dict(n.json(dict=True)),
             {
-                'id': '192.168.0.1',
-                'label': 'test node',
-                'local_addresses': ['10.0.0.1'],
-                'properties': {
-                    'gateway': True,
-                    'created': JSONEncoder().default(n.created),
-                    'modified': JSONEncoder().default(n.modified),
+                "id": "192.168.0.1",
+                "label": "test node",
+                "local_addresses": ["10.0.0.1"],
+                "properties": {
+                    "gateway": True,
+                    "created": JSONEncoder().default(n.created),
+                    "modified": JSONEncoder().default(n.modified),
                 },
             },
         )
         self.assertIsInstance(n.json(), str)
-        with self.subTest('testing original=True'):
+        with self.subTest("testing original=True"):
             netjson = n.json(dict=True, original=True)
-            self.assertNotIn('created', netjson['properties'])
-            self.assertNotIn('modified', netjson['properties'])
+            self.assertNotIn("created", netjson["properties"])
+            self.assertNotIn("modified", netjson["properties"])
 
     def test_get_from_address(self):
         t = self.topology_model.objects.first()
-        n = t._create_node(addresses=['192.168.0.1', '10.0.0.1'])
+        n = t._create_node(addresses=["192.168.0.1", "10.0.0.1"])
         n.full_clean()
         n.save()
         self.assertIsInstance(
-            self.node_model.get_from_address('192.168.0.1', t), self.node_model
+            self.node_model.get_from_address("192.168.0.1", t), self.node_model
         )
         self.assertIsInstance(
-            self.node_model.get_from_address('10.0.0.1', t), self.node_model
+            self.node_model.get_from_address("10.0.0.1", t), self.node_model
         )
-        self.assertIsNone(self.node_model.get_from_address('wrong', t))
+        self.assertIsNone(self.node_model.get_from_address("wrong", t))
 
     def test_count_address(self):
         t = self.topology_model.objects.first()
-        self.assertEqual(self.node_model.count_address('192.168.0.1', t), 1)
-        self.assertEqual(self.node_model.count_address('0.0.0.0', t), 0)
+        self.assertEqual(self.node_model.count_address("192.168.0.1", t), 1)
+        self.assertEqual(self.node_model.count_address("0.0.0.0", t), 0)
 
     def test_count_address_issue_58(self):
         t = self.topology_model.objects.first()
-        n1 = t._create_node(addresses=['Benz_Kalloni'])
+        n1 = t._create_node(addresses=["Benz_Kalloni"])
         n1.full_clean()
         n1.save()
-        n2 = t._create_node(addresses=['Kalloni'])
+        n2 = t._create_node(addresses=["Kalloni"])
         n2.full_clean()
         n2.save()
-        self.assertEqual(self.node_model.count_address('Benz_Kalloni', t), 1)
-        self.assertEqual(self.node_model.count_address('Kalloni', t), 1)
+        self.assertEqual(self.node_model.count_address("Benz_Kalloni", t), 1)
+        self.assertEqual(self.node_model.count_address("Kalloni", t), 1)
 
     def test_node_auto_org(self):
         t = self.topology_model.objects.first()
         n = self.node_model(
-            label='TestNode', addresses=['192.168.0.1'], properties={}, topology=t
+            label="TestNode", addresses=["192.168.0.1"], properties={}, topology=t
         )
         n.full_clean()
         self.assertEqual(n.organization, t.organization)
@@ -144,60 +144,60 @@ def test_node_auto_org(self):
     def test_user_properties_in_json(self):
         t = self.topology_model.objects.first()
         n = t._create_node(
-            addresses=['192.168.0.1'], label='test node', properties=None
+            addresses=["192.168.0.1"], label="test node", properties=None
         )
-        n.properties = {'gateway': True}
-        n.user_properties = {'user_property': True}
+        n.properties = {"gateway": True}
+        n.user_properties = {"user_property": True}
         n.full_clean()
         n.save()
 
-        with self.subTest('view json with original False'):
+        with self.subTest("view json with original False"):
             data = n.json(dict=True)
-            self.assertIn('gateway', data['properties'])
-            self.assertIn('user_property', data['properties'])
+            self.assertIn("gateway", data["properties"])
+            self.assertIn("user_property", data["properties"])
 
-        with self.subTest('view json with original True'):
+        with self.subTest("view json with original True"):
             data = n.json(dict=True, original=True)
-            self.assertIn('gateway', data['properties'])
-            self.assertNotIn('user_property', data['properties'])
+            self.assertIn("gateway", data["properties"])
+            self.assertNotIn("user_property", data["properties"])
 
     def test_get_organization(self):
         org = self._get_org()
         org_topology = Topology.objects.first()
         shared_topology = self._create_topology(
-            label='Shared Topology', organization=None
+            label="Shared Topology", organization=None
         )
 
-        with self.subTest('Shared nodes can belong to shared topology'):
+        with self.subTest("Shared nodes can belong to shared topology"):
             try:
                 shared_node = self._create_node(
-                    label='shared_node',
-                    addresses=['192.168.0.6'],
+                    label="shared_node",
+                    addresses=["192.168.0.6"],
                     topology=shared_topology,
                     organization=None,
                 )
             except ValidationError:
-                self.fail('Shared topology failed to include shared node.')
+                self.fail("Shared topology failed to include shared node.")
             shared_node.refresh_from_db()
             self.assertEqual(shared_node.organization, None)
 
-        with self.subTest('Non-shared nodes can belong to shared topology'):
+        with self.subTest("Non-shared nodes can belong to shared topology"):
             try:
                 org_node = self._create_node(
-                    label='org_node',
-                    addresses=['192.168.0.7'],
+                    label="org_node",
+                    addresses=["192.168.0.7"],
                     topology=shared_topology,
                     organization=org,
                 )
             except ValidationError:
-                self.fail('Shared topology failed to include non-shared node.')
+                self.fail("Shared topology failed to include non-shared node.")
             org_node.refresh_from_db()
             self.assertEqual(org_node.organization, org)
 
-        with self.subTest('Node gets organization of non-shared topology'):
+        with self.subTest("Node gets organization of non-shared topology"):
             node = self._create_node(
-                label='node',
-                addresses=['192.168.0.8'],
+                label="node",
+                addresses=["192.168.0.8"],
                 topology=org_topology,
                 organization=None,
             )
@@ -205,12 +205,12 @@ def test_get_organization(self):
             self.assertEqual(node.organization, org)
 
         with self.subTest(
-            'ValidationError on different organization node and topology'
+            "ValidationError on different organization node and topology"
         ):
             with self.assertRaises(ValidationError):
                 self._create_node(
-                    label='node',
-                    addresses=['192.168.0.9'],
+                    label="node",
+                    addresses=["192.168.0.9"],
                     topology=org_topology,
-                    organization=self._get_org('default'),
+                    organization=self._get_org("default"),
                 )
diff --git a/openwisp_network_topology/tests/test_selenium.py b/openwisp_network_topology/tests/test_selenium.py
index 1d55138e..1c62cf12 100644
--- a/openwisp_network_topology/tests/test_selenium.py
+++ b/openwisp_network_topology/tests/test_selenium.py
@@ -11,12 +11,12 @@
 
 from .utils import CreateGraphObjectsMixin, LoadMixin
 
-Link = load_model('topology', 'Link')
-Node = load_model('topology', 'Node')
-Topology = load_model('topology', 'Topology')
+Link = load_model("topology", "Link")
+Node = load_model("topology", "Node")
+Topology = load_model("topology", "Topology")
 
 
-@tag('selenium_tests')
+@tag("selenium_tests")
 class TestTopologyGraphVisualizer(
     TestOrganizationMixin,
     CreateGraphObjectsMixin,
@@ -24,15 +24,15 @@ class TestTopologyGraphVisualizer(
     SeleniumTestMixin,
     StaticLiveServerTestCase,
 ):
-    app_label = 'topology'
+    app_label = "topology"
     node_model = Node
     link_model = Link
     topology_model = Topology
-    _EXPECTED_KEYS = ['Label', 'Protocol', 'Version', 'Metric', 'Nodes', 'Links']
+    _EXPECTED_KEYS = ["Label", "Protocol", "Version", "Metric", "Nodes", "Links"]
 
     @property
     def prefix(self):
-        return f'admin:{self.app_label}'
+        return f"admin:{self.app_label}"
 
     def setUp(self):
         org = self._create_org()
@@ -41,14 +41,14 @@ def setUp(self):
         )
         self.topology = self._create_topology(organization=org)
         self._create_node(
-            label='node1',
-            addresses=['192.168.0.1'],
+            label="node1",
+            addresses=["192.168.0.1"],
             topology=self.topology,
             organization=org,
         )
         self._create_node(
-            label='node2',
-            addresses=['192.168.0.2'],
+            label="node2",
+            addresses=["192.168.0.2"],
             topology=self.topology,
             organization=org,
         )
@@ -59,27 +59,27 @@ def tearDown(self):
 
     def _assert_topology_graph(self, hide_loading_overlay=True):
         if hide_loading_overlay:
-            self.hide_loading_overlay('loadingContainer')
-        self.find_element(By.CLASS_NAME, 'sideBarHandle').click()
-        self.wait_for_visibility(By.CLASS_NAME, 'njg-metaInfoContainer')
-        self.wait_for_visibility(By.XPATH, '//div[1]/canvas')
+            self.hide_loading_overlay("loadingContainer")
+        self.find_element(By.CLASS_NAME, "sideBarHandle").click()
+        self.wait_for_visibility(By.CLASS_NAME, "njg-metaInfoContainer")
+        self.wait_for_visibility(By.XPATH, "//div[1]/canvas")
         self.assertEqual(self.get_browser_logs(), [])
         topology_graph_dict = self.topology.json(dict=True)
-        topology_graph_label_keys = self.find_elements(By.CSS_SELECTOR, '.njg-keyLabel')
+        topology_graph_label_keys = self.find_elements(By.CSS_SELECTOR, ".njg-keyLabel")
         topology_graph_label_values = self.find_elements(
-            By.CSS_SELECTOR, '.njg-valueLabel'
+            By.CSS_SELECTOR, ".njg-valueLabel"
         )
         self.assertEqual(len(topology_graph_label_keys), len(self._EXPECTED_KEYS))
         # ensure correct topology graph labels are present
         for key in topology_graph_label_keys:
             self.assertIn(key.text, self._EXPECTED_KEYS)
         expected_label_values = [
-            topology_graph_dict['label'],
-            topology_graph_dict['protocol'],
-            topology_graph_dict['version'],
-            topology_graph_dict['metric'],
-            str(len(topology_graph_dict['nodes'])),
-            str(len(topology_graph_dict['links'])),
+            topology_graph_dict["label"],
+            topology_graph_dict["protocol"],
+            topology_graph_dict["version"],
+            topology_graph_dict["metric"],
+            str(len(topology_graph_dict["nodes"])),
+            str(len(topology_graph_dict["links"])),
         ]
         for label_value, expected_value in zip(
             topology_graph_label_values, expected_label_values
@@ -87,56 +87,56 @@ def _assert_topology_graph(self, hide_loading_overlay=True):
             self.assertEqual(label_value.text, expected_value)
 
     def test_topology_admin_view_graph_visualizer(self):
-        path = reverse(f'{self.prefix}_topology_change', args=[self.topology.pk])
+        path = reverse(f"{self.prefix}_topology_change", args=[self.topology.pk])
         self.login()
         self.open(path)
-        self.find_element(By.CSS_SELECTOR, 'input.visualizelink').click()
+        self.find_element(By.CSS_SELECTOR, "input.visualizelink").click()
         self._assert_topology_graph()
 
     def test_unpublished_topology_admin_view_graph_visualizer(self):
         self.topology_model.objects.update(published=False)
-        path = reverse(f'{self.prefix}_topology_change', args=[self.topology.pk])
+        path = reverse(f"{self.prefix}_topology_change", args=[self.topology.pk])
         self.login()
         self.open(path)
-        self.find_element(By.CSS_SELECTOR, 'input.visualizelink').click()
+        self.find_element(By.CSS_SELECTOR, "input.visualizelink").click()
         self._assert_topology_graph()
 
     def test_topology_non_admin_view_graph_visualizer(self):
         self.login()
-        self.open(reverse('topology_list'), html_container='body.frontend')
+        self.open(reverse("topology_list"), html_container="body.frontend")
         self.find_element(By.XPATH, "//ul[@id='menu']/li/a").click()
         self._assert_topology_graph()
 
     def test_topology_admin_visualizer_multiple_close_btn_append(self):
-        path = reverse(f'{self.prefix}_topology_change', args=[self.topology.pk])
+        path = reverse(f"{self.prefix}_topology_change", args=[self.topology.pk])
         self.login()
         self.open(path)
-        self.find_element(By.CSS_SELECTOR, 'input.visualizelink').click()
+        self.find_element(By.CSS_SELECTOR, "input.visualizelink").click()
         self._assert_topology_graph()
-        self.find_element(By.CLASS_NAME, 'closeBtn').click()
+        self.find_element(By.CLASS_NAME, "closeBtn").click()
         # Now try to open visualizer
         # again and make sure only single
         # 'closeBtn' element is present in the DOM
-        self.find_element(By.CSS_SELECTOR, 'input.visualizelink').click()
+        self.find_element(By.CSS_SELECTOR, "input.visualizelink").click()
         self._assert_topology_graph()
         try:
-            self.find_element(By.CLASS_NAME, 'closeBtn').click()
+            self.find_element(By.CLASS_NAME, "closeBtn").click()
         except ElementClickInterceptedException:
             self.fail('Multiple "closeBtn" are present in the visualizer DOM')
 
     def test_topology_admin_esc_key_close_visualizer(self):
-        path = reverse(f'{self.prefix}_topology_change', args=[self.topology.pk])
+        path = reverse(f"{self.prefix}_topology_change", args=[self.topology.pk])
         self.login()
         self.open(path)
-        self.find_element(By.CSS_SELECTOR, 'input.visualizelink').click()
+        self.find_element(By.CSS_SELECTOR, "input.visualizelink").click()
         self._assert_topology_graph()
         # Try to close the visualizer with the "Esc" key.
-        body = self.find_element(By.TAG_NAME, 'body')
+        body = self.find_element(By.TAG_NAME, "body")
         body.send_keys(Keys.ESCAPE)
         # Open the visualizer again and make sure no JS errors
         # are thrown when the visualizer is closed again
-        self.find_element(By.CSS_SELECTOR, 'input.visualizelink').click()
+        self.find_element(By.CSS_SELECTOR, "input.visualizelink").click()
         self._assert_topology_graph(hide_loading_overlay=False)
-        self.find_element(By.CLASS_NAME, 'closeBtn').click()
+        self.find_element(By.CLASS_NAME, "closeBtn").click()
         console_logs = self.get_browser_logs()
         self.assertEqual(console_logs, [])
diff --git a/openwisp_network_topology/tests/test_snapshot.py b/openwisp_network_topology/tests/test_snapshot.py
index 1e6f0b93..e8f8745c 100644
--- a/openwisp_network_topology/tests/test_snapshot.py
+++ b/openwisp_network_topology/tests/test_snapshot.py
@@ -1,7 +1,7 @@
 import swapper
 from django.test import TestCase
 
-Snapshot = swapper.load_model('topology', 'Snapshot')
+Snapshot = swapper.load_model("topology", "Snapshot")
 
 
 class TestSnapshot(TestCase):
diff --git a/openwisp_network_topology/tests/test_topology.py b/openwisp_network_topology/tests/test_topology.py
index 81b8bdb4..ec8f78fe 100644
--- a/openwisp_network_topology/tests/test_topology.py
+++ b/openwisp_network_topology/tests/test_topology.py
@@ -11,9 +11,9 @@
 
 from .utils import CreateGraphObjectsMixin, CreateOrgMixin, LoadMixin
 
-Link = swapper.load_model('topology', 'Link')
-Node = swapper.load_model('topology', 'Node')
-Topology = swapper.load_model('topology', 'Topology')
+Link = swapper.load_model("topology", "Link")
+Node = swapper.load_model("topology", "Node")
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TestTopology(CreateOrgMixin, CreateGraphObjectsMixin, LoadMixin, TestCase):
@@ -26,20 +26,20 @@ def setUp(self):
         org = self._create_org()
         t = self._create_topology(organization=org)
         self._create_node(
-            label='node1', addresses=['192.168.0.1'], topology=t, organization=org
+            label="node1", addresses=["192.168.0.1"], topology=t, organization=org
         )
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t, organization=org
+            label="node2", addresses=["192.168.0.2"], topology=t, organization=org
         )
 
     def _get_nodes(self):
         return self.node_model.objects.all()
 
-    def _set_receive(self, expiration_time=0, parser='netdiff.NetJsonParser'):
+    def _set_receive(self, expiration_time=0, parser="netdiff.NetJsonParser"):
         t = self.topology_model.objects.first()
         t.parser = parser
-        t.strategy = 'receive'
-        t.key = 'test'
+        t.strategy = "receive"
+        t.key = "test"
         t.expiration_time = expiration_time
         t.save()
         return t
@@ -59,24 +59,24 @@ def test_json_empty(self):
         self.assertDictEqual(
             graph,
             {
-                'type': 'NetworkGraph',
-                'protocol': 'OLSR',
-                'version': '0.8',
-                'metric': 'ETX',
-                'label': t.label,
-                'id': str(t.id),
-                'parser': t.parser,
-                'created': t.created,
-                'modified': t.modified,
-                'nodes': [],
-                'links': [],
+                "type": "NetworkGraph",
+                "protocol": "OLSR",
+                "version": "0.8",
+                "metric": "ETX",
+                "label": t.label,
+                "id": str(t.id),
+                "parser": t.parser,
+                "created": t.created,
+                "modified": t.modified,
+                "nodes": [],
+                "links": [],
             },
         )
 
     def test_json(self):
         node1, node2 = self._get_nodes()
         t = self.topology_model.objects.first()
-        node3 = t._create_node(addresses=['192.168.0.3'], label='node3')
+        node3 = t._create_node(addresses=["192.168.0.3"], label="node3")
         node3.save()
         link = t._create_link(source=node1, target=node2, cost=1)
         link.save()
@@ -86,21 +86,21 @@ def test_json(self):
         self.assertDictEqual(
             dict(graph),
             {
-                'type': 'NetworkGraph',
-                'protocol': 'OLSR',
-                'version': '0.8',
-                'metric': 'ETX',
-                'label': t.label,
-                'id': str(t.id),
-                'parser': t.parser,
-                'created': t.created,
-                'modified': t.modified,
-                'nodes': [
+                "type": "NetworkGraph",
+                "protocol": "OLSR",
+                "version": "0.8",
+                "metric": "ETX",
+                "label": t.label,
+                "id": str(t.id),
+                "parser": t.parser,
+                "created": t.created,
+                "modified": t.modified,
+                "nodes": [
                     dict(node1.json(dict=True)),
                     dict(node2.json(dict=True)),
                     dict(node3.json(dict=True)),
                 ],
-                'links': [dict(link.json(dict=True)), dict(l2.json(dict=True))],
+                "links": [dict(link.json(dict=True)), dict(l2.json(dict=True))],
             },
         )
         self.assertIsInstance(t.json(), str)
@@ -108,48 +108,48 @@ def test_json(self):
     @responses.activate
     def test_empty_diff(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
+            "http://127.0.0.1:9090",
             body=t.json(original=True),
-            content_type='application/json',
+            content_type="application/json",
         )
         self.assertDictEqual(
-            t.diff(), {'added': None, 'removed': None, 'changed': None}
+            t.diff(), {"added": None, "removed": None, "changed": None}
         )
 
     @responses.activate
     def test_update_all_attributes(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         t.protocol = None
         t.version = None
         t.metric = None
         t.update()
         t.refresh_from_db()
-        self.assertEqual(t.protocol, 'OLSR')
-        self.assertEqual(t.version, '0.8')
-        self.assertEqual(t.metric, 'ETX')
+        self.assertEqual(t.protocol, "OLSR")
+        self.assertEqual(t.version, "0.8")
+        self.assertEqual(t.metric, "ETX")
 
     @responses.activate
     def test_update_added(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         t.update()
@@ -157,13 +157,13 @@ def test_update_added(self):
         self.assertEqual(self.link_model.objects.count(), 1)
         node1 = self.node_model.objects.get(addresses__contains='"192.168.0.1"')
         node2 = self.node_model.objects.get(addresses__contains='"192.168.0.2"')
-        self.assertEqual(node1.local_addresses, ['10.0.0.1'])
-        self.assertEqual(node1.properties, {'gateway': True})
+        self.assertEqual(node1.local_addresses, ["10.0.0.1"])
+        self.assertEqual(node1.properties, {"gateway": True})
         link = self.link_model.objects.first()
         self.assertIn(link.source, [node1, node2])
         self.assertIn(link.target, [node1, node2])
         self.assertEqual(link.cost, 1.0)
-        self.assertEqual(link.properties, {'pretty': True})
+        self.assertEqual(link.properties, {"pretty": True})
         # ensure repeating the action is idempotent
         t.update()
         self.assertEqual(self.node_model.objects.count(), 2)
@@ -172,120 +172,120 @@ def test_update_added(self):
     @responses.activate
     def test_update_changed(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         t.update()
-        node = self.node_model.get_from_address('192.168.0.2', topology=t)
-        self.assertEqual(node.label, '')
-        self.assertEqual(node.addresses, ['192.168.0.2'])
+        node = self.node_model.get_from_address("192.168.0.2", topology=t)
+        self.assertEqual(node.label, "")
+        self.assertEqual(node.addresses, ["192.168.0.2"])
         link = self.link_model.objects.first()
-        self.assertEqual(link.properties, {'pretty': True})
+        self.assertEqual(link.properties, {"pretty": True})
         self.assertEqual(link.cost, 1.0)
-        self.assertEqual(link.cost_text, '10 Mbps')
+        self.assertEqual(link.cost_text, "10 Mbps")
         # now change
-        t.url = t.url.replace('9090', '9091')
+        t.url = t.url.replace("9090", "9091")
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9091',
-            body=self._load('static/netjson-2-links.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9091",
+            body=self._load("static/netjson-2-links.json"),
+            content_type="application/json",
         )
         t.update()
         self.assertEqual(self.node_model.objects.count(), 3)
         # test changed properties for existing node
-        node = self.node_model.get_from_address('192.168.0.2', topology=t)
-        self.assertEqual(node.label, 'node2')
-        self.assertEqual(node.addresses, ['192.168.0.2', '10.0.0.2'])
+        node = self.node_model.get_from_address("192.168.0.2", topology=t)
+        self.assertEqual(node.label, "node2")
+        self.assertEqual(node.addresses, ["192.168.0.2", "10.0.0.2"])
         # test added node with properties
-        node = self.node_model.get_from_address('192.168.0.3', topology=t)
-        self.assertEqual(node.label, 'node3')
-        self.assertEqual(node.addresses, ['192.168.0.3', '10.0.0.3'])
+        node = self.node_model.get_from_address("192.168.0.3", topology=t)
+        self.assertEqual(node.label, "node3")
+        self.assertEqual(node.addresses, ["192.168.0.3", "10.0.0.3"])
         self.assertEqual(self.link_model.objects.count(), 2)
         link.refresh_from_db()
-        self.assertEqual(link.properties, {'pretty': True})
+        self.assertEqual(link.properties, {"pretty": True})
         self.assertEqual(link.cost, 1.5)
-        self.assertEqual(link.cost_text, '15 Mbps')
+        self.assertEqual(link.cost_text, "15 Mbps")
         link = self.link_model.get_from_nodes(
-            source='192.168.0.1', target='192.168.0.3', topology=t
+            source="192.168.0.1", target="192.168.0.3", topology=t
         )
-        self.assertEqual(link.properties, {'pretty': False})
+        self.assertEqual(link.properties, {"pretty": False})
         self.assertEqual(link.cost, 2.0)
-        self.assertEqual(link.cost_text, '20 Mbps')
+        self.assertEqual(link.cost_text, "20 Mbps")
 
     @responses.activate
     def test_update_removed(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-2-links.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-2-links.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         t.update()
         self.assertEqual(self.node_model.objects.count(), 3)
         self.assertEqual(self.link_model.objects.count(), 2)
         # now change
-        t.url = t.url.replace('9090', '9091')
+        t.url = t.url.replace("9090", "9091")
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9091',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9091",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         t.update()
         self.assertEqual(self.node_model.objects.count(), 3)
         self.assertEqual(self.link_model.objects.count(), 2)
-        self.assertEqual(self.link_model.objects.filter(status='down').count(), 1)
-        link = self.link_model.objects.filter(status='down').first()
-        self.assertIn('192.168.0.3', [link.source.netjson_id, link.target.netjson_id])
+        self.assertEqual(self.link_model.objects.filter(status="down").count(), 1)
+        link = self.link_model.objects.filter(status="down").first()
+        self.assertIn("192.168.0.3", [link.source.netjson_id, link.target.netjson_id])
         self.assertEqual(link.cost, 2.0)
 
     @responses.activate
     def test_update_status_existing_link(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         n1 = self.node_model.objects.all()[0]
         n2 = self.node_model.objects.all()[1]
         link = t._create_link(
-            source=n1, target=n2, cost=1, status='down', properties={'pretty': True}
+            source=n1, target=n2, cost=1, status="down", properties={"pretty": True}
         )
         link.full_clean()
         link.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         t.update()
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         link.refresh_from_db()
-        self.assertEqual(link.status, 'up')
+        self.assertEqual(link.status, "up")
 
     def test_topology_url_empty(self):
         t = self.topology_model(
-            label='test', parser='netdiff.NetJsonParser', strategy='fetch'
+            label="test", parser="netdiff.NetJsonParser", strategy="fetch"
         )
         with self.assertRaises(ValidationError):
             t.full_clean()
 
     def test_topology_key_empty(self):
         t = self.topology_model(
-            label='test', parser='netdiff.NetJsonParser', strategy='receive', key=''
+            label="test", parser="netdiff.NetJsonParser", strategy="receive", key=""
         )
         with self.assertRaises(ValidationError):
             t.full_clean()
@@ -293,19 +293,19 @@ def test_topology_key_empty(self):
     def _test_receive_added(self, expiration_time=0):
         self.node_model.objects.all().delete()
         t = self._set_receive(expiration_time)
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         node1 = self.node_model.objects.get(addresses__contains='"192.168.0.1"')
         node2 = self.node_model.objects.get(addresses__contains='"192.168.0.2"')
-        self.assertEqual(node1.local_addresses, ['10.0.0.1'])
-        self.assertEqual(node1.properties, {'gateway': True})
+        self.assertEqual(node1.local_addresses, ["10.0.0.1"])
+        self.assertEqual(node1.properties, {"gateway": True})
         link = self.link_model.objects.first()
         self.assertIn(link.source, [node1, node2])
         self.assertIn(link.target, [node1, node2])
         self.assertEqual(link.cost, 1.0)
-        self.assertEqual(link.properties, {'pretty': True})
+        self.assertEqual(link.properties, {"pretty": True})
         # ensure repeating the action is idempotent
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 2)
@@ -317,11 +317,11 @@ def test_receive_added(self):
     def _test_receive_changed(self, expiration_time=0):
         t = self._set_receive(expiration_time)
         self.node_model.objects.all().delete()
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         t.receive(data)
         link = self.link_model.objects.first()
         # now change
-        data = self._load('static/netjson-2-links.json')
+        data = self._load("static/netjson-2-links.json")
         t.receive(data)
         link.refresh_from_db()
         self.assertEqual(self.node_model.objects.count(), 3)
@@ -334,67 +334,67 @@ def test_receive_changed(self):
     def test_receive_removed(self):
         t = self._set_receive()
         self.node_model.objects.all().delete()
-        data = self._load('static/netjson-2-links.json')
+        data = self._load("static/netjson-2-links.json")
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 3)
         self.assertEqual(self.link_model.objects.count(), 2)
         # now change
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 3)
         self.assertEqual(self.link_model.objects.count(), 2)
-        self.assertEqual(self.link_model.objects.filter(status='down').count(), 1)
-        link = self.link_model.objects.filter(status='down').first()
-        self.assertIn('192.168.0.3', [link.source.netjson_id, link.target.netjson_id])
+        self.assertEqual(self.link_model.objects.filter(status="down").count(), 1)
+        link = self.link_model.objects.filter(status="down").first()
+        self.assertIn("192.168.0.3", [link.source.netjson_id, link.target.netjson_id])
         self.assertEqual(link.cost, 2.0)
 
     def test_receive_removed_bug(self):
-        t = self._set_receive(parser='netdiff.OpenvpnParser')
+        t = self._set_receive(parser="netdiff.OpenvpnParser")
         self.node_model.objects.all().delete()
-        data = self._load('static/openvpn.txt')
+        data = self._load("static/openvpn.txt")
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 4)
         self.assertEqual(self.link_model.objects.count(), 3)
-        self.assertEqual(self.link_model.objects.filter(status='up').count(), 3)
-        self.assertEqual(self.link_model.objects.filter(status='down').count(), 0)
-        data = self._load('static/openvpn-0-links.txt')
+        self.assertEqual(self.link_model.objects.filter(status="up").count(), 3)
+        self.assertEqual(self.link_model.objects.filter(status="down").count(), 0)
+        data = self._load("static/openvpn-0-links.txt")
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 4)
         self.assertEqual(self.link_model.objects.count(), 3)
-        self.assertEqual(self.link_model.objects.filter(status='down').count(), 3)
-        self.assertEqual(self.link_model.objects.filter(status='up').count(), 0)
+        self.assertEqual(self.link_model.objects.filter(status="down").count(), 3)
+        self.assertEqual(self.link_model.objects.filter(status="up").count(), 0)
         t.refresh_from_db()
         netjson = t.json(dict=True)
         for link in self.link_model.objects.all():
-            for attr in ['status', 'status_changed', 'created', 'modified']:
-                with self.subTest(f'{attr} should not be saved in properties ({link})'):
+            for attr in ["status", "status_changed", "created", "modified"]:
+                with self.subTest(f"{attr} should not be saved in properties ({link})"):
                     self.assertNotIn(attr, link.properties)
-        for link in netjson['links']:
-            with self.subTest(f'status should be down ({link})'):
-                self.assertEqual(link['properties']['status'], 'down')
-            for attr in ['status_changed', 'created', 'modified']:
-                with self.subTest(f'{attr} should be present in properties ({link})'):
-                    self.assertIn(attr, link['properties'])
-        for node in netjson['nodes']:
-            for attr in ['created', 'modified']:
-                with self.subTest(f'{attr} should be present in properties ({node})'):
-                    self.assertIn(attr, node['properties'])
+        for link in netjson["links"]:
+            with self.subTest(f"status should be down ({link})"):
+                self.assertEqual(link["properties"]["status"], "down")
+            for attr in ["status_changed", "created", "modified"]:
+                with self.subTest(f"{attr} should be present in properties ({link})"):
+                    self.assertIn(attr, link["properties"])
+        for node in netjson["nodes"]:
+            for attr in ["created", "modified"]:
+                with self.subTest(f"{attr} should be present in properties ({node})"):
+                    self.assertIn(attr, node["properties"])
 
     def test_receive_status_existing_link(self):
         t = self._set_receive()
         n1 = self.node_model.objects.all()[0]
         n2 = self.node_model.objects.all()[1]
         link = t._create_link(
-            source=n1, target=n2, cost=1, status='down', properties={'pretty': True}
+            source=n1, target=n2, cost=1, status="down", properties={"pretty": True}
         )
         link.full_clean()
         link.save()
-        data = self._load('static/netjson-1-link.json')
+        data = self._load("static/netjson-1-link.json")
         t.receive(data)
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         link.refresh_from_db()
-        self.assertEqual(link.status, 'up')
+        self.assertEqual(link.status, "up")
 
     def test_multiple_receive_added(self):
         self._test_receive_added(expiration_time=50)
@@ -405,55 +405,55 @@ def test_multiple_receive_changed(self):
     def test_multiple_receive_removed(self):
         with freeze_time() as frozen_time:
             t = self._set_receive(expiration_time=1)
-            data = self._load('static/netjson-2-links.json')
+            data = self._load("static/netjson-2-links.json")
             for sleep_time in [0, 1.2, 1]:
                 frozen_time.tick(timedelta(seconds=sleep_time))
                 t.receive(data)
                 self.assertEqual(self.node_model.objects.count(), 3)
                 self.assertEqual(self.link_model.objects.count(), 2)
                 self.assertEqual(
-                    self.link_model.objects.filter(status='down').count(), 0
+                    self.link_model.objects.filter(status="down").count(), 0
                 )
             # receive change
-            data = self._load('static/netjson-1-link.json')
+            data = self._load("static/netjson-1-link.json")
             t.receive(data)
             self.assertEqual(self.node_model.objects.count(), 3)
             self.assertEqual(self.link_model.objects.count(), 2)
             # expiration_time has not expired
-            self.assertEqual(self.link_model.objects.filter(status='down').count(), 0)
+            self.assertEqual(self.link_model.objects.filter(status="down").count(), 0)
             # expiration_time has now expired for 1 link
             frozen_time.tick(timedelta(seconds=1.2))
             t.receive(data)
-            self.assertEqual(self.link_model.objects.filter(status='down').count(), 1)
-            link = self.link_model.objects.filter(status='down').first()
+            self.assertEqual(self.link_model.objects.filter(status="down").count(), 1)
+            link = self.link_model.objects.filter(status="down").first()
             self.assertIn(
-                '192.168.0.3', [link.source.netjson_id, link.target.netjson_id]
+                "192.168.0.3", [link.source.netjson_id, link.target.netjson_id]
             )
             self.assertEqual(link.cost, 2.0)
 
     def test_multiple_receive_split_network(self):
         def _assert_split_topology(self, topology):
             self.assertEqual(self.node_model.objects.count(), 4)
-            self.assertEqual(self.link_model.objects.filter(status='up').count(), 2)
-            self.assertEqual(self.link_model.objects.filter(status='down').count(), 0)
+            self.assertEqual(self.link_model.objects.filter(status="up").count(), 2)
+            self.assertEqual(self.link_model.objects.filter(status="down").count(), 0)
             link = self.link_model.get_from_nodes(
-                '192.168.0.1', '192.168.0.2', topology
+                "192.168.0.1", "192.168.0.2", topology
             )
             self.assertIsNotNone(link)
-            self.assertEqual(link.status, 'up')
+            self.assertEqual(link.status, "up")
             self.assertEqual(link.cost, 1.0)
             link = self.link_model.get_from_nodes(
-                '192.168.0.10', '192.168.0.20', topology
+                "192.168.0.10", "192.168.0.20", topology
             )
             self.assertIsNotNone(link)
-            self.assertEqual(link.status, 'up')
+            self.assertEqual(link.status, "up")
             self.assertEqual(link.cost, 1.1)
 
         with freeze_time() as frozen_time:
             self.node_model.objects.all().delete()
             t = self._set_receive(expiration_time=1)
-            network1 = self._load('static/netjson-1-link.json')
-            network2 = self._load('static/split-network.json')
+            network1 = self._load("static/netjson-1-link.json")
+            network2 = self._load("static/split-network.json")
             t.receive(network1)
             t.receive(network2)
             _assert_split_topology(self, t)
@@ -470,9 +470,9 @@ def test_very_long_addresses(self):
         see https://github.com/netjson/django-netjsongraph/issues/6
         """
         t = self._set_receive()
-        data = self._load('static/very-long-addresses.json')
+        data = self._load("static/very-long-addresses.json")
         t.receive(data)
-        n = self.node_model.get_from_address('2001:4e12:452a:1:172::10', t)
+        n = self.node_model.get_from_address("2001:4e12:452a:1:172::10", t)
         self.assertEqual(len("".join(n.addresses)), 568)
 
     def test_save_snapshot(self):
@@ -486,46 +486,46 @@ def test_save_snapshot(self):
         self.assertFalse(s.created == s.modified)
 
     def test_label_addition(self):
-        t = self._set_receive(parser='netdiff.OpenvpnParser')
+        t = self._set_receive(parser="netdiff.OpenvpnParser")
         t.save()
         t.node_set.all().delete()
-        data = self._load('static/openvpn.txt')
+        data = self._load("static/openvpn.txt")
         t.receive(data)
         self.assertEqual(t.node_set.count(), 4)
         labels = []
         for node in t.node_set.all():
             labels.append(node.label)
-        self.assertIn('Syskrack', labels)
-        self.assertIn('Kali-Matera', labels)
-        self.assertIn('pomezia', labels)
+        self.assertIn("Syskrack", labels)
+        self.assertIn("Kali-Matera", labels)
+        self.assertIn("pomezia", labels)
 
     def test_issue_58(self):
         self.node_model.objects.all().delete()
         self.link_model.objects.all().delete()
         t = self._set_receive()
-        data = self._load('static/issue-58.json')
+        data = self._load("static/issue-58.json")
         t.receive(data)
         self.assertEqual(t.node_set.all().count(), 13)
         self.assertEqual(t.link_set.all().count(), 11)
 
     @capture_any_output()
     def test_update_added_items_regression_74_first(self):
-        t = self._set_receive(parser='netdiff.OpenvpnParser')
+        t = self._set_receive(parser="netdiff.OpenvpnParser")
         t.save()
         node = t.node_set.first()
-        items = {'nodes': [{'id': node.netjson_id}]}
+        items = {"nodes": [{"id": node.netjson_id}]}
         t._update_added_items(items)
 
     def test_update_added_items_regression_74_second(self):
-        t = self._set_receive(parser='netdiff.OpenvpnParser')
+        t = self._set_receive(parser="netdiff.OpenvpnParser")
         t.save()
-        items = {'nodes': [{'id': 'bogus'}]}
+        items = {"nodes": [{"id": "bogus"}]}
         t._update_changed_items(items)
 
     def test_receive_regression(self):
-        t = self._set_receive(parser='netdiff.OpenvpnParser', expiration_time=120)
+        t = self._set_receive(parser="netdiff.OpenvpnParser", expiration_time=120)
         t.save()
-        data = self._load('static/openvpn.txt')
+        data = self._load("static/openvpn.txt")
         pre_existing_nodes = Node.objects.count()
         node1 = Node.objects.first()
         node2 = Node.objects.last()
@@ -535,9 +535,9 @@ def test_receive_regression(self):
             self.assertEqual(t.link_set.count(), 3)
             # create new link not included in the topology data
             link = self._create_link(
-                source=node1, target=node2, status='up', topology=t, cost=1
+                source=node1, target=node2, status="up", topology=t, cost=1
             )
-            self.assertEqual(link.status, 'up')
+            self.assertEqual(link.status, "up")
             modified = link.modified
             # after 61 seconds we receive new (empty) data
             # we expect the link status to remain unchanged
@@ -546,7 +546,7 @@ def test_receive_regression(self):
             frozen_time.tick(timedelta(seconds=61))
             t.receive(data)
             link.refresh_from_db()
-            self.assertEqual(link.status, 'up')
+            self.assertEqual(link.status, "up")
             self.assertEqual(link.modified, modified)
             # hen the topology data is received again later
             # the expiration time is passed and we expect
@@ -554,5 +554,5 @@ def test_receive_regression(self):
             frozen_time.tick(timedelta(seconds=61))
             t.receive(data)
             link.refresh_from_db()
-            self.assertEqual(link.status, 'down')
+            self.assertEqual(link.status, "down")
             self.assertNotEqual(link.modified, modified)
diff --git a/openwisp_network_topology/tests/test_upgrader_script.py b/openwisp_network_topology/tests/test_upgrader_script.py
index 0dac84b0..3f1e4447 100644
--- a/openwisp_network_topology/tests/test_upgrader_script.py
+++ b/openwisp_network_topology/tests/test_upgrader_script.py
@@ -8,8 +8,8 @@
 from swapper import load_model
 
 User = get_user_model()
-Organization = load_model('openwisp_users', 'Organization')
-Topology = load_model('topology', 'Topology')
+Organization = load_model("openwisp_users", "Organization")
+Topology = load_model("topology", "Topology")
 
 
 class TestUpgradeFromDjangoNetjsongraph(TestCase):
@@ -17,26 +17,26 @@ def test_success(self):
         self.assertEqual(Topology.objects.count(), 0)
         commandOutput = StringIO()
         static_path = os.path.join(
-            os.path.dirname(__file__), 'static', 'upgrader_script'
+            os.path.dirname(__file__), "static", "upgrader_script"
         )
         call_command(
-            'upgrade_from_django_netjsongraph', backup=static_path, stdout=commandOutput
+            "upgrade_from_django_netjsongraph", backup=static_path, stdout=commandOutput
         )
-        self.assertIn('Migration Process Complete!', commandOutput.getvalue())
-        os.remove(os.path.join(static_path, 'group_loaded.json'))
-        os.remove(os.path.join(static_path, 'netjsongraph_loaded.json'))
-        os.remove(os.path.join(static_path, 'user_loaded.json'))
+        self.assertIn("Migration Process Complete!", commandOutput.getvalue())
+        os.remove(os.path.join(static_path, "group_loaded.json"))
+        os.remove(os.path.join(static_path, "netjsongraph_loaded.json"))
+        os.remove(os.path.join(static_path, "user_loaded.json"))
         self.assertEqual(Topology.objects.count(), 1)
         try:
-            Topology.objects.get(label='default')
+            Topology.objects.get(label="default")
         except Topology.DoesNotExist:
             self.fail('Topology "default" not created!')
         try:
-            user = User.objects.get(username='sample')
+            user = User.objects.get(username="sample")
             group = Group.objects.filter(user=user).first()
             permissions = Permission.objects.filter(user=user).first()
-            self.assertEqual('sample', group.name)
-            self.assertEqual('add_logentry', permissions.codename)
+            self.assertEqual("sample", group.name)
+            self.assertEqual("add_logentry", permissions.codename)
         except User.DoesNotExist:
             self.fail('User "sample" not created!')
 
@@ -44,7 +44,7 @@ def test_files_not_found(self):
         commandOutput = StringIO()
         with self.assertRaises(FileNotFoundError):
             call_command(
-                'upgrade_from_django_netjsongraph',
+                "upgrade_from_django_netjsongraph",
                 backup=os.path.join(os.path.dirname(__file__)),
                 stdout=commandOutput,
             )
@@ -53,8 +53,8 @@ def test_organization_not_found(self):
         commandOutput = StringIO()
         with self.assertRaises(Organization.DoesNotExist):
             call_command(
-                'upgrade_from_django_netjsongraph',
-                backup=os.path.join(os.path.dirname(__file__), 'static'),
-                organization='00000000-0000-0000-0000-000000000000',
+                "upgrade_from_django_netjsongraph",
+                backup=os.path.join(os.path.dirname(__file__), "static"),
+                organization="00000000-0000-0000-0000-000000000000",
                 stdout=commandOutput,
             )
diff --git a/openwisp_network_topology/tests/test_users_integration.py b/openwisp_network_topology/tests/test_users_integration.py
index 696bb344..385fb939 100644
--- a/openwisp_network_topology/tests/test_users_integration.py
+++ b/openwisp_network_topology/tests/test_users_integration.py
@@ -9,10 +9,10 @@ class TestUsersIntegration(TestBasicUsersIntegration):
     is_integration_test = True
 
     _notifications_params = {
-        'notificationsetting_set-TOTAL_FORMS': 0,
-        'notificationsetting_set-INITIAL_FORMS': 0,
-        'notificationsetting_set-MIN_NUM_FORMS': 0,
-        'notificationsetting_set-MAX_NUM_FORMS': 0,
+        "notificationsetting_set-TOTAL_FORMS": 0,
+        "notificationsetting_set-INITIAL_FORMS": 0,
+        "notificationsetting_set-MIN_NUM_FORMS": 0,
+        "notificationsetting_set-MAX_NUM_FORMS": 0,
     }
 
     def _get_org_edit_form_inline_params(self, user, org):
diff --git a/openwisp_network_topology/tests/test_utils.py b/openwisp_network_topology/tests/test_utils.py
index 6e114ce3..8f906b6e 100644
--- a/openwisp_network_topology/tests/test_utils.py
+++ b/openwisp_network_topology/tests/test_utils.py
@@ -13,11 +13,11 @@
 from .. import settings as app_settings
 from .utils import CreateGraphObjectsMixin, CreateOrgMixin, LoadMixin
 
-Organization = swapper.load_model('openwisp_users', 'Organization')
-Link = swapper.load_model('topology', 'Link')
-Node = swapper.load_model('topology', 'Node')
-Snapshot = swapper.load_model('topology', 'Snapshot')
-Topology = swapper.load_model('topology', 'Topology')
+Organization = swapper.load_model("openwisp_users", "Organization")
+Link = swapper.load_model("topology", "Link")
+Node = swapper.load_model("topology", "Node")
+Snapshot = swapper.load_model("topology", "Snapshot")
+Topology = swapper.load_model("topology", "Topology")
 
 
 @contextmanager
@@ -45,15 +45,15 @@ def setUp(self):
         org = self._create_org()
         t = self._create_topology(organization=org)
         self._create_node(
-            label='node1', addresses=['192.168.0.1'], topology=t, organization=org
+            label="node1", addresses=["192.168.0.1"], topology=t, organization=org
         )
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t, organization=org
+            label="node2", addresses=["192.168.0.2"], topology=t, organization=org
         )
 
     def _create_link(self, **kwargs):
         org = self.organization_model.objects.first()
-        options = dict(cost='1', cost_text='one', properties={}, organization=org)
+        options = dict(cost="1", cost_text="one", properties={}, organization=org)
         options.update(kwargs)
         link = self.link_model(**options)
         link.full_clean()
@@ -63,28 +63,28 @@ def _create_link(self, **kwargs):
     @responses.activate
     def test_update_all_method(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
-        self.topology_model.update_all('testnetwork')
+        self.topology_model.update_all("testnetwork")
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         # test exception
-        t.url = t.url.replace('9090', '9091')
+        t.url = t.url.replace("9090", "9091")
         t.save()
         self.node_model.objects.all().delete()
         self.link_model.objects.all().delete()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9091',
-            body=self._load('static/netjson-invalid.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9091",
+            body=self._load("static/netjson-invalid.json"),
+            content_type="application/json",
         )
         # capture output
         output = StringIO()
@@ -93,54 +93,54 @@ def test_update_all_method(self):
 
         self.assertEqual(self.node_model.objects.count(), 1)
         self.assertEqual(self.link_model.objects.count(), 0)
-        self.assertIn('Failed to', output.getvalue())
+        self.assertIn("Failed to", output.getvalue())
 
     @responses.activate
     def test_update_topology_command(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         self.topology_model.update_all()
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         # test exception
-        t.url = t.url.replace('9090', '9091')
+        t.url = t.url.replace("9090", "9091")
         t.save()
         self.node_model.objects.all().delete()
         self.link_model.objects.all().delete()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9091',
-            body=self._load('static/netjson-invalid.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9091",
+            body=self._load("static/netjson-invalid.json"),
+            content_type="application/json",
         )
         # capture output
         output = StringIO()
         with redirect_stdout(output):
-            call_command('update_topology')
+            call_command("update_topology")
 
         self.assertEqual(self.node_model.objects.count(), 1)
         self.assertEqual(self.link_model.objects.count(), 0)
-        self.assertIn('Failed to', output.getvalue())
+        self.assertIn("Failed to", output.getvalue())
 
     @responses.activate
     def test_update_all_method_unpublished(self):
         t = self.topology_model.objects.first()
         t.published = False
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
-            body=self._load('static/netjson-1-link.json'),
-            content_type='application/json',
+            "http://127.0.0.1:9090",
+            body=self._load("static/netjson-1-link.json"),
+            content_type="application/json",
         )
         self.node_model.objects.all().delete()
         self.topology_model.update_all()
@@ -150,14 +150,14 @@ def test_update_all_method_unpublished(self):
     @responses.activate
     def test_delete_expired_links(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         # should not delete
         almost_expired_date = now() - timedelta(days=app_settings.LINK_EXPIRATION - 10)
         n1 = self.node_model.objects.all()[0]
         n2 = self.node_model.objects.all()[1]
         link = self._create_link(
-            source=n1, target=n2, cost=1, status='down', topology=t
+            source=n1, target=n2, cost=1, status="down", topology=t
         )
         self.link_model.objects.filter(pk=link.pk).update(
             created=almost_expired_date, modified=almost_expired_date
@@ -174,11 +174,11 @@ def test_delete_expired_links(self):
         )
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
+            "http://127.0.0.1:9090",
             body=empty_topology,
-            content_type='application/json',
+            content_type="application/json",
         )
-        self.topology_model.update_all('testnetwork')
+        self.topology_model.update_all("testnetwork")
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         # should delete
@@ -186,18 +186,18 @@ def test_delete_expired_links(self):
         self.link_model.objects.filter(pk=link.pk).update(
             created=expired_date, modified=expired_date
         )
-        self.topology_model.update_all('testnetwork')
+        self.topology_model.update_all("testnetwork")
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 0)
 
     @responses.activate
     def test_delete_expired_nodes(self):
-        NODE_EXPIRATION = getattr(app_settings, 'NODE_EXPIRATION')
+        NODE_EXPIRATION = getattr(app_settings, "NODE_EXPIRATION")
         # Test with the default value(False)
         # Should not delete
-        setattr(app_settings, 'NODE_EXPIRATION', False)
+        setattr(app_settings, "NODE_EXPIRATION", False)
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         expired_date = now() - timedelta(days=60)
         n1 = self.node_model.objects.all()[0]
@@ -220,16 +220,16 @@ def test_delete_expired_nodes(self):
         )
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
+            "http://127.0.0.1:9090",
             body=empty_topology,
-            content_type='application/json',
+            content_type="application/json",
         )
-        self.topology_model.update_all('testnetwork')
+        self.topology_model.update_all("testnetwork")
         self.assertEqual(self.node_model.objects.count(), 2)
 
         # Test with a custom value
         # Should delete
-        setattr(app_settings, 'NODE_EXPIRATION', 60)
+        setattr(app_settings, "NODE_EXPIRATION", 60)
         expired_date = now() - timedelta(days=app_settings.NODE_EXPIRATION + 10)
         self.node_model.objects.filter(pk=n1.pk).update(
             created=expired_date, modified=expired_date
@@ -237,21 +237,21 @@ def test_delete_expired_nodes(self):
         self.node_model.objects.filter(pk=n2.pk).update(
             created=expired_date, modified=expired_date
         )
-        self.topology_model.update_all('testnetwork')
+        self.topology_model.update_all("testnetwork")
         self.assertEqual(self.node_model.objects.count(), 0)
         self.assertEqual(self.link_model.objects.count(), 0)
         # Set the setting to it's original value
-        setattr(app_settings, 'NODE_EXPIRATION', NODE_EXPIRATION)
+        setattr(app_settings, "NODE_EXPIRATION", NODE_EXPIRATION)
 
     @responses.activate
     def test_delete_expired_disabled(self):
         t = self.topology_model.objects.first()
-        t.parser = 'netdiff.NetJsonParser'
+        t.parser = "netdiff.NetJsonParser"
         t.save()
         n1 = self.node_model.objects.all()[0]
         n2 = self.node_model.objects.all()[1]
         link = self._create_link(
-            source=n1, target=n2, cost=1, status='down', topology=t
+            source=n1, target=n2, cost=1, status="down", topology=t
         )
         expired_date = now() - timedelta(days=app_settings.LINK_EXPIRATION + 10)
         self.link_model.objects.filter(pk=link.pk).update(
@@ -269,13 +269,13 @@ def test_delete_expired_disabled(self):
         )
         responses.add(
             responses.GET,
-            'http://127.0.0.1:9090',
+            "http://127.0.0.1:9090",
             body=empty_topology,
-            content_type='application/json',
+            content_type="application/json",
         )
         ORIGINAL_LINK_EXPIRATION = int(app_settings.LINK_EXPIRATION)
         app_settings.LINK_EXPIRATION = False
-        self.topology_model.update_all('testnetwork')
+        self.topology_model.update_all("testnetwork")
         self.assertEqual(self.node_model.objects.count(), 2)
         self.assertEqual(self.link_model.objects.count(), 1)
         app_settings.LINK_EXPIRATION = ORIGINAL_LINK_EXPIRATION
@@ -285,7 +285,7 @@ def test_save_snapshot_all_method(self, **kwargs):
         options = dict(organization=org)
         options.update(**kwargs)
         self.assertEqual(self.snapshot_model.objects.count(), 0)
-        self.topology_model.save_snapshot_all('testnetwork')
+        self.topology_model.save_snapshot_all("testnetwork")
         self.assertEqual(self.snapshot_model.objects.count(), 1)
         self._create_topology(**options)
         self.topology_model.save_snapshot_all()
@@ -295,5 +295,5 @@ def test_save_snapshot_command(self):
         self.assertEqual(self.snapshot_model.objects.count(), 0)
         output = StringIO()
         with redirect_stdout(output):
-            call_command('save_snapshot')
+            call_command("save_snapshot")
         self.assertEqual(self.snapshot_model.objects.count(), 1)
diff --git a/openwisp_network_topology/tests/test_visualizer.py b/openwisp_network_topology/tests/test_visualizer.py
index a105da24..66ac32bd 100644
--- a/openwisp_network_topology/tests/test_visualizer.py
+++ b/openwisp_network_topology/tests/test_visualizer.py
@@ -10,9 +10,9 @@
 from .. import settings as app_settings
 from .utils import CreateGraphObjectsMixin, UnpublishMixin
 
-Node = swapper.load_model('topology', 'Node')
-Topology = swapper.load_model('topology', 'Topology')
-OrganizationUser = swapper.load_model('openwisp_users', 'OrganizationUser')
+Node = swapper.load_model("topology", "Node")
+Topology = swapper.load_model("topology", "Topology")
+OrganizationUser = swapper.load_model("openwisp_users", "OrganizationUser")
 
 
 class TestVisualizer(
@@ -23,38 +23,38 @@ class TestVisualizer(
 
     def setUp(self):
         org = self._create_org()
-        user = self._create_admin(username='visualizer', email='visualizer@email.com')
+        user = self._create_admin(username="visualizer", email="visualizer@email.com")
         self._create_org_user(user=user, organization=org)
         self.client.force_login(user)
         t = self._create_topology(organization=org)
         self._create_node(
-            label='node1', addresses=['192.168.0.1'], topology=t, organization=org
+            label="node1", addresses=["192.168.0.1"], topology=t, organization=org
         )
         self._create_node(
-            label='node2', addresses=['192.168.0.2'], topology=t, organization=org
+            label="node2", addresses=["192.168.0.2"], topology=t, organization=org
         )
 
     def test_list(self):
-        response = self.client.get(reverse('topology_list'))
-        self.assertContains(response, 'TestNetwork')
+        response = self.client.get(reverse("topology_list"))
+        self.assertContains(response, "TestNetwork")
 
     def test_detail(self):
         t = self.topology_model.objects.first()
-        response = self.client.get(reverse('topology_detail', args=[t.pk]))
+        response = self.client.get(reverse("topology_detail", args=[t.pk]))
         self.assertContains(response, t.pk)
         # ensure switcher is present
-        self.assertContains(response, 'njg-switcher')
-        self.assertContains(response, 'njg-datepicker')
+        self.assertContains(response, "njg-switcher")
+        self.assertContains(response, "njg-datepicker")
 
     def test_list_unpublished(self):
         self._unpublish()
-        response = self.client.get(reverse('topology_list'))
-        self.assertNotContains(response, 'TestNetwork')
+        response = self.client.get(reverse("topology_list"))
+        self.assertNotContains(response, "TestNetwork")
 
     def test_detail_unpublished(self):
         self._unpublish()
         t = self.topology_model.objects.first()
-        response = self.client.get(reverse('topology_detail', args=[t.pk]))
+        response = self.client.get(reverse("topology_detail", args=[t.pk]))
         self.assertEqual(response.status_code, 404)
 
     def test_detail_uuid_exception(self):
@@ -63,7 +63,7 @@ def test_detail_uuid_exception(self):
         """
         t = self.topology_model.objects.first()
         response = self.client.get(
-            reverse('topology_detail', args=['{0}-wrong'.format(t.pk)])
+            reverse("topology_detail", args=["{0}-wrong".format(t.pk)])
         )
         self.assertEqual(response.status_code, 404)
 
@@ -71,24 +71,24 @@ def _test_visualizer_with_unauthenticated_user(self, url):
         self.client.logout()
         r = self.client.get(url)
         self.assertContains(
-            r, 'Authentication credentials were not provided.', status_code=403
+            r, "Authentication credentials were not provided.", status_code=403
         )
 
     def _test_visualizer_with_not_a_manager_user(self, user, url, is_detail=False):
         OrganizationUser.objects.filter(user=user).delete()
-        perm = Permission.objects.filter(codename__endswith='topology')
+        perm = Permission.objects.filter(codename__endswith="topology")
         user.user_permissions.add(*perm)
         self.client.force_login(user)
         r = self.client.get(url)
         if is_detail:
             detail = (
-                'User is not a manager of the organization to '
-                'which the requested resource belongs.'
+                "User is not a manager of the organization to "
+                "which the requested resource belongs."
             )
             self.assertContains(r, detail, status_code=403)
         else:
             self.assertEqual(r.status_code, 200)
-            self.assertNotContains(r, 'TestNetwork')
+            self.assertNotContains(r, "TestNetwork")
             self.assertNotEqual(Topology.objects.all().count(), 0)
 
     def _test_visualizer_with_not_permitted_user(self, user, url):
@@ -97,57 +97,57 @@ def _test_visualizer_with_not_permitted_user(self, user, url):
         self.client.force_login(user)
         r = self.client.get(url)
         self.assertContains(
-            r, 'You do not have permission to perform this action.', status_code=403
+            r, "You do not have permission to perform this action.", status_code=403
         )
 
     def test_list_visualizer_with_auth_enabled(self):
-        user = self._create_user(username='list-user', email='list@email.com')
-        url = reverse('topology_list')
+        user = self._create_user(username="list-user", email="list@email.com")
+        url = reverse("topology_list")
 
-        with self.subTest('test list visualizer with not auth user'):
+        with self.subTest("test list visualizer with not auth user"):
             self._test_visualizer_with_unauthenticated_user(url)
 
-        with self.subTest('test list visualizer with not permitted user'):
+        with self.subTest("test list visualizer with not permitted user"):
             self._test_visualizer_with_not_permitted_user(user, url)
 
-        with self.subTest('test list visualizer with not a manager user'):
+        with self.subTest("test list visualizer with not a manager user"):
             self._test_visualizer_with_not_a_manager_user(user, url)
 
     def test_detail_visualizer_with_auth_enabled(self):
-        user = self._create_user(username='detail-user', email='detail@email.com')
+        user = self._create_user(username="detail-user", email="detail@email.com")
         t = self.topology_model.objects.first()
-        url = reverse('topology_detail', args=[t.pk])
+        url = reverse("topology_detail", args=[t.pk])
 
-        with self.subTest('test detail visualizer with not auth user'):
+        with self.subTest("test detail visualizer with not auth user"):
             self._test_visualizer_with_unauthenticated_user(url)
 
-        with self.subTest('test detail visualizer with not permitted user'):
+        with self.subTest("test detail visualizer with not permitted user"):
             self._test_visualizer_with_not_permitted_user(user, url)
 
-        with self.subTest('test detail visualizer with not a manager user'):
+        with self.subTest("test detail visualizer with not a manager user"):
             self._test_visualizer_with_not_a_manager_user(user, url, is_detail=True)
 
     def _successful_visualizer_tests(self):
-        with self.subTest('test superuser on list visualizer'):
-            r = self.client.get(reverse('topology_list'))
-            self.assertContains(r, 'TestNetwork')
+        with self.subTest("test superuser on list visualizer"):
+            r = self.client.get(reverse("topology_list"))
+            self.assertContains(r, "TestNetwork")
 
-        with self.subTest('test superuser on detail visualizer'):
+        with self.subTest("test superuser on detail visualizer"):
             t = self.topology_model.objects.first()
-            r = self.client.get(reverse('topology_detail', args=[t.pk]))
+            r = self.client.get(reverse("topology_detail", args=[t.pk]))
             self.assertContains(r, t.pk)
 
     def test_visualizer_with_auth_enabled_superuser(self):
-        user = self._create_admin(username='super-visualizer', email='s@email.com')
+        user = self._create_admin(username="super-visualizer", email="s@email.com")
         self.client.force_login(user)
         self._successful_visualizer_tests()
 
-    @patch.object(app_settings, 'TOPOLOGY_API_AUTH_REQUIRED', return_value=False)
+    @patch.object(app_settings, "TOPOLOGY_API_AUTH_REQUIRED", return_value=False)
     def test_visualizer_with_auth_disabled(self, mocked):
         self._successful_visualizer_tests()
 
-    @patch.object(app_settings, 'TOPOLOGY_API_AUTH_REQUIRED', return_value=False)
+    @patch.object(app_settings, "TOPOLOGY_API_AUTH_REQUIRED", return_value=False)
     def test_visualizer_with_auth_disabled_superuser(self, mocked):
-        user = self._create_admin(username='super-visualizer', email='s@email.com')
+        user = self._create_admin(username="super-visualizer", email="s@email.com")
         self.client.force_login(user)
         self._successful_visualizer_tests()
diff --git a/openwisp_network_topology/tests/test_websockets.py b/openwisp_network_topology/tests/test_websockets.py
index d0c1a027..6b2e2159 100644
--- a/openwisp_network_topology/tests/test_websockets.py
+++ b/openwisp_network_topology/tests/test_websockets.py
@@ -14,9 +14,9 @@
 from .. import settings as app_settings
 from .utils import CreateGraphObjectsMixin
 
-Topology = load_model('topology', 'Topology')
-Node = load_model('topology', 'Node')
-Link = load_model('topology', 'Link')
+Topology = load_model("topology", "Topology")
+Node = load_model("topology", "Node")
+Link = load_model("topology", "Link")
 
 
 @pytest.mark.asyncio
@@ -25,17 +25,17 @@ class TestTopologySockets(CreateGraphObjectsMixin, TestOrganizationMixin):
     node_model = Node
     link_model = Link
     topology_model = Topology
-    application = import_string(getattr(settings, 'ASGI_APPLICATION'))
+    application = import_string(getattr(settings, "ASGI_APPLICATION"))
 
     async def _get_communicator(self, admin_client, topology_id):
-        session_id = admin_client.cookies['sessionid'].value
+        session_id = admin_client.cookies["sessionid"].value
         communicator = WebsocketCommunicator(
             self.application,
-            path=f'ws/network-topology/topology/{topology_id}/',
+            path=f"ws/network-topology/topology/{topology_id}/",
             headers=[
                 (
-                    b'cookie',
-                    f'sessionid={session_id}'.encode('ascii'),
+                    b"cookie",
+                    f"sessionid={session_id}".encode("ascii"),
                 )
             ],
         )
@@ -52,7 +52,7 @@ async def _assert_connection_superuser(self, admin_client, conn=True):
     async def _assert_connection_org_manager(self, client, view_perm=True, conn=True):
         org = await database_sync_to_async(self._create_org)()
         test_user = await database_sync_to_async(self._create_user)(
-            username='test-user-org-manager', email='test@orgmanger.com', is_staff=True
+            username="test-user-org-manager", email="test@orgmanger.com", is_staff=True
         )
         await database_sync_to_async(self._create_org_user)(
             is_admin=True, user=test_user, organization=org
@@ -60,7 +60,7 @@ async def _assert_connection_org_manager(self, client, view_perm=True, conn=True
         t = await database_sync_to_async(self._create_topology)(organization=org)
         if view_perm:
             topology_view_permission = await Permission.objects.aget(
-                codename='view_topology'
+                codename="view_topology"
             )
             await test_user.user_permissions.aadd(topology_view_permission)
         await database_sync_to_async(client.force_login)(test_user)
@@ -70,7 +70,7 @@ async def _assert_connection_org_manager(self, client, view_perm=True, conn=True
         await communicator.disconnect()
 
     async def _assert_connection_unauth_user(self, client, conn=True):
-        client.cookies['sessionid'] = 'unauthenticated_user'
+        client.cookies["sessionid"] = "unauthenticated_user"
         org = await database_sync_to_async(self._create_org)()
         t = await database_sync_to_async(self._create_topology)(organization=org)
         communicator = await self._get_communicator(client, t.pk)
@@ -90,15 +90,15 @@ async def test_consumer_connection_org_manager_without_view_perm(self, client):
     async def test_consumer_connection_unauth_user(self, client):
         await self._assert_connection_unauth_user(client, conn=False)
 
-    @patch.object(app_settings, 'TOPOLOGY_API_AUTH_REQUIRED', False)
+    @patch.object(app_settings, "TOPOLOGY_API_AUTH_REQUIRED", False)
     async def test_consumer_connection_auth_disabled_superuser(self, admin_client):
         await self._assert_connection_superuser(admin_client)
 
-    @patch.object(app_settings, 'TOPOLOGY_API_AUTH_REQUIRED', False)
+    @patch.object(app_settings, "TOPOLOGY_API_AUTH_REQUIRED", False)
     async def test_consumer_connection_auth_disabled_org_manager(self, client):
         await self._assert_connection_org_manager(client)
 
-    @patch.object(app_settings, 'TOPOLOGY_API_AUTH_REQUIRED', False)
+    @patch.object(app_settings, "TOPOLOGY_API_AUTH_REQUIRED", False)
     async def test_consumer_connection_auth_disabled_unauth_user(self, client):
         await self._assert_connection_unauth_user(client)
 
@@ -123,20 +123,20 @@ async def test_node_topology_update(self, admin_user, admin_client):
         )
         response = await communicator.receive_json_from()
         expected_response = await database_sync_to_async(topo.json)()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
-        node.label = 'test'
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
+        node.label = "test"
         await database_sync_to_async(node.full_clean)()
         await database_sync_to_async(node.save)()
         expected_response = await database_sync_to_async(topo.json)()
         response = await communicator.receive_json_from()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
         await node.adelete()
         expected_response = await database_sync_to_async(topo.json)()
         response = await communicator.receive_json_from()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
         await communicator.disconnect()
 
     async def test_link_topology_update(self, admin_user, admin_client):
@@ -146,11 +146,11 @@ async def test_link_topology_update(self, admin_user, admin_client):
         connected, _ = await communicator.connect()
         assert connected is True
         node1 = await database_sync_to_async(self._create_node)(
-            topology=topo, label='node-0', organization=org
+            topology=topo, label="node-0", organization=org
         )
         response = await communicator.receive_json_from()
         node2 = await database_sync_to_async(self._create_node)(
-            topology=topo, label='node-1', organization=org
+            topology=topo, label="node-1", organization=org
         )
         response = await communicator.receive_json_from()
         link = await database_sync_to_async(self._create_link)(
@@ -158,20 +158,20 @@ async def test_link_topology_update(self, admin_user, admin_client):
         )
         response = await communicator.receive_json_from()
         expected_response = await database_sync_to_async(topo.json)()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
-        link.status = 'down'
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
+        link.status = "down"
         await database_sync_to_async(link.full_clean)()
         await link.asave()
         expected_response = await database_sync_to_async(topo.json)()
         response = await communicator.receive_json_from()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
         await link.adelete()
         expected_response = await database_sync_to_async(topo.json)()
         response = await communicator.receive_json_from()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
         await communicator.disconnect()
 
     async def test_topology_properties_update(self, admin_user, admin_client):
@@ -180,11 +180,11 @@ async def test_topology_properties_update(self, admin_user, admin_client):
         communicator = await self._get_communicator(admin_client, topo.pk)
         connected, _ = await communicator.connect()
         assert connected is True
-        topo.name = 'test'
+        topo.name = "test"
         await database_sync_to_async(topo.full_clean)()
         await topo.asave()
         expected_response = await database_sync_to_async(topo.json)()
         response = await communicator.receive_json_from()
-        assert response['topology'] is not None
-        assert response['topology'] == expected_response
+        assert response["topology"] is not None
+        assert response["topology"] == expected_response
         await communicator.disconnect()
diff --git a/openwisp_network_topology/tests/utils.py b/openwisp_network_topology/tests/utils.py
index 7ca8f993..6140ce42 100644
--- a/openwisp_network_topology/tests/utils.py
+++ b/openwisp_network_topology/tests/utils.py
@@ -5,12 +5,12 @@
 
 from openwisp_utils.tests import TimeLoggingTestRunner
 
-Organization = swapper.load_model('openwisp_users', 'Organization')
+Organization = swapper.load_model("openwisp_users", "Organization")
 
 
 class CreateOrgMixin(object):
     def _create_org(self, **kwargs):
-        options = dict(name='test-organization')
+        options = dict(name="test-organization")
         options.update(kwargs)
         org = Organization(**options)
         org.save()
@@ -20,15 +20,15 @@ def _create_org(self, **kwargs):
 class CreateGraphObjectsMixin(object):
     def _create_topology(self, **kwargs):
         options = dict(
-            label='TestNetwork',
-            parser='netdiff.OlsrParser',
-            strategy='fetch',
-            url='http://127.0.0.1:9090',
-            protocol='OLSR',
-            version='0.8',
-            metric='ETX',
-            created='2017-07-10T20:02:52.483Z',
-            modified='2015-07-14T20:02:52.483Z',
+            label="TestNetwork",
+            parser="netdiff.OlsrParser",
+            strategy="fetch",
+            url="http://127.0.0.1:9090",
+            protocol="OLSR",
+            version="0.8",
+            metric="ETX",
+            created="2017-07-10T20:02:52.483Z",
+            modified="2015-07-14T20:02:52.483Z",
         )
         options.update(kwargs)
         t = self.topology_model(**options)
@@ -38,10 +38,10 @@ def _create_topology(self, **kwargs):
 
     def _create_node(self, **kwargs):
         options = dict(
-            label='TestNode',
-            addresses=['192.168.0.1'],
-            created='2017-07-10T20:02:52.483Z',
-            modified='2017-07-14T20:02:52.483Z',
+            label="TestNode",
+            addresses=["192.168.0.1"],
+            created="2017-07-10T20:02:52.483Z",
+            modified="2017-07-14T20:02:52.483Z",
             properties={},
         )
         options.update(kwargs)
@@ -51,7 +51,7 @@ def _create_node(self, **kwargs):
         return n
 
     def _create_link(self, **kwargs):
-        options = dict(cost='1', cost_text='one', properties={})
+        options = dict(cost="1", cost_text="one", properties={})
         options.update(kwargs)
         link = self.link_model(**options)
         link.full_clean()
diff --git a/openwisp_network_topology/urls.py b/openwisp_network_topology/urls.py
index cc673180..ecf8e96b 100644
--- a/openwisp_network_topology/urls.py
+++ b/openwisp_network_topology/urls.py
@@ -4,7 +4,7 @@
 from .visualizer import urls as visualizer_urls
 
 urlpatterns = [
-    path('accounts/', include('openwisp_users.accounts.urls')),
-    path('api/v1/', include(api)),
-    path('topology/', include(visualizer_urls)),
+    path("accounts/", include("openwisp_users.accounts.urls")),
+    path("api/v1/", include(api)),
+    path("topology/", include(visualizer_urls)),
 ]
diff --git a/openwisp_network_topology/utils.py b/openwisp_network_topology/utils.py
index e28801a4..78ce9000 100644
--- a/openwisp_network_topology/utils.py
+++ b/openwisp_network_topology/utils.py
@@ -16,15 +16,15 @@ def print_info(message):  # pragma no cover
     """
     print info message if calling from management command ``update_all``
     """
-    if 'update_topology' in sys.argv:
-        print('{0}\n'.format(message))
+    if "update_topology" in sys.argv:
+        print("{0}\n".format(message))
 
 
 def get_object_or_404(model, pk, **kwargs):
     """
     retrieves topology with specified arguments or raises 404
     """
-    kwargs.update({'pk': pk, 'published': True})
+    kwargs.update({"pk": pk, "published": True})
     try:
         return get_obj_or_404(model, **kwargs)
     except ValidationError:
@@ -37,36 +37,36 @@ def get_api_urls(views_module):
     """
     urls = [
         path(
-            'network-topology/topology/',
+            "network-topology/topology/",
             views_module.network_collection,
-            name='network_collection',
+            name="network_collection",
         ),
         path(
-            'network-topology/topology/<uuid:pk>/',
+            "network-topology/topology/<uuid:pk>/",
             views_module.network_graph,
-            name='network_graph',
+            name="network_graph",
         ),
         path(
-            'network-topology/topology/<uuid:pk>/history/',
+            "network-topology/topology/<uuid:pk>/history/",
             views_module.network_graph_history,
-            name='network_graph_history',
+            name="network_graph_history",
         ),
         path(
-            'network-topology/topology/<uuid:pk>/receive/',
+            "network-topology/topology/<uuid:pk>/receive/",
             views_module.receive_topology,
-            name='receive_topology',
+            name="receive_topology",
         ),
-        path('network-topology/node/', views_module.node_list, name='node_list'),
+        path("network-topology/node/", views_module.node_list, name="node_list"),
         path(
-            'network-topology/node/<uuid:pk>/',
+            "network-topology/node/<uuid:pk>/",
             views_module.node_detail,
-            name='node_detail',
+            name="node_detail",
         ),
-        path('network-topology/link/', views_module.link_list, name='link_list'),
+        path("network-topology/link/", views_module.link_list, name="link_list"),
         path(
-            'network-topology/link/<uuid:pk>/',
+            "network-topology/link/<uuid:pk>/",
             views_module.link_detail,
-            name='link_detail',
+            name="link_detail",
         ),
     ]
     return urls
@@ -77,11 +77,11 @@ def get_visualizer_urls(views_module):
     used by third party apps to reduce boilerplate
     """
     urls = [
-        path('', views_module.topology_list, name='topology_list'),
+        path("", views_module.topology_list, name="topology_list"),
         re_path(
-            r'^topology/(?P<pk>[^/]+)/$',
+            r"^topology/(?P<pk>[^/]+)/$",
             views_module.topology_detail,
-            name='topology_detail',
+            name="topology_detail",
         ),
     ]
     return urls
diff --git a/openwisp_network_topology/visualizer/__init__.py b/openwisp_network_topology/visualizer/__init__.py
index 4045c0fd..194a8829 100644
--- a/openwisp_network_topology/visualizer/__init__.py
+++ b/openwisp_network_topology/visualizer/__init__.py
@@ -5,18 +5,18 @@
 
 class GraphVisualizerUrls:
     def get_graph_urls(self, request, pk):
-        graph_path = reverse('network_graph', urlconf=TOPOLOGY_API_URLCONF, args=[pk])
+        graph_path = reverse("network_graph", urlconf=TOPOLOGY_API_URLCONF, args=[pk])
         history_path = reverse(
-            'network_graph_history', urlconf=TOPOLOGY_API_URLCONF, args=[pk]
+            "network_graph_history", urlconf=TOPOLOGY_API_URLCONF, args=[pk]
         )
         if TOPOLOGY_API_BASEURL:
-            graph_url = '{}{}'.format(TOPOLOGY_API_BASEURL, graph_path)
-            history_url = '{}{}'.format(TOPOLOGY_API_BASEURL, history_path)
+            graph_url = "{}{}".format(TOPOLOGY_API_BASEURL, graph_path)
+            history_url = "{}{}".format(TOPOLOGY_API_BASEURL, history_path)
         else:
-            graph_url = '{0}://{1}{2}'.format(
+            graph_url = "{0}://{1}{2}".format(
                 request.scheme, request.get_host(), graph_path
             )
-            history_url = '{0}://{1}{2}'.format(
+            history_url = "{0}://{1}{2}".format(
                 request.scheme, request.get_host(), history_path
             )
         return graph_url, history_url
diff --git a/openwisp_network_topology/visualizer/views.py b/openwisp_network_topology/visualizer/views.py
index f11f15ba..741e8b16 100644
--- a/openwisp_network_topology/visualizer/views.py
+++ b/openwisp_network_topology/visualizer/views.py
@@ -8,7 +8,7 @@
 from ..utils import get_object_or_404
 from . import GraphVisualizerUrls
 
-Topology = swapper.load_model('topology', 'Topology')
+Topology = swapper.load_model("topology", "Topology")
 
 
 class TopologyListView(View):
@@ -24,8 +24,8 @@ def get(self, request):
             topologies = topologies.filter(organization__in=user.organizations_managed)
         return render(
             request,
-            'netjsongraph/list.html',
-            {'topologies': topologies, 'VISUALIZER_CSS': VISUALIZER_CSS},
+            "netjsongraph/list.html",
+            {"topologies": topologies, "VISUALIZER_CSS": VISUALIZER_CSS},
         )
 
 
@@ -41,19 +41,19 @@ def get(self, request, pk):
                 return auth_perm
             if not user.is_manager(topology.organization):
                 detail = _(
-                    'User is not a manager of the organization to '
-                    'which the requested resource belongs.'
+                    "User is not a manager of the organization to "
+                    "which the requested resource belongs."
                 )
                 return HttpResponseForbidden(detail)
         graph_url, history_url = self.get_graph_urls(request, pk)
         return render(
             request,
-            'netjsongraph/detail.html',
+            "netjsongraph/detail.html",
             {
-                'topology': topology,
-                'graph_url': graph_url,
-                'history_url': history_url,
-                'VISUALIZER_CSS': VISUALIZER_CSS,
+                "topology": topology,
+                "graph_url": graph_url,
+                "history_url": history_url,
+                "VISUALIZER_CSS": VISUALIZER_CSS,
             },
         )
 
@@ -62,13 +62,13 @@ def check_auth_perm(request):
     user = request.user
     app_label = Topology._meta.app_label.lower()
     model = Topology._meta.object_name.lower()
-    change_perm = f'{app_label}.change_{model}'
-    view_perm = f'{app_label}.view_{model}'
+    change_perm = f"{app_label}.change_{model}"
+    view_perm = f"{app_label}.view_{model}"
     if not user.is_authenticated:
-        return HttpResponseForbidden(_('Authentication credentials were not provided.'))
+        return HttpResponseForbidden(_("Authentication credentials were not provided."))
     if not (user.has_perm(change_perm) or user.has_perm(view_perm)):
         return HttpResponseForbidden(
-            _('You do not have permission to perform this action.')
+            _("You do not have permission to perform this action.")
         )
 
 
diff --git a/runtests.py b/runtests.py
index 4ca53d15..4b7be7e2 100755
--- a/runtests.py
+++ b/runtests.py
@@ -3,27 +3,27 @@
 import os
 import sys
 
-sys.path.insert(0, 'tests')
-os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'openwisp2.settings')
+sys.path.insert(0, "tests")
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "openwisp2.settings")
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     import pytest
     from django.core.management import execute_from_command_line
 
     args = sys.argv
-    args.insert(1, 'test')
-    if not os.environ.get('SAMPLE_APP', False):
-        args.insert(2, 'openwisp_network_topology')
-        args.insert(3, 'openwisp_network_topology.integrations.device')
+    args.insert(1, "test")
+    if not os.environ.get("SAMPLE_APP", False):
+        args.insert(2, "openwisp_network_topology")
+        args.insert(3, "openwisp_network_topology.integrations.device")
     else:
-        args.insert(2, 'openwisp2')
-    if os.environ.get('WIFI_MESH', False):
-        args.extend(['--tag', 'wifi_mesh'])
+        args.insert(2, "openwisp2")
+    if os.environ.get("WIFI_MESH", False):
+        args.extend(["--tag", "wifi_mesh"])
     else:
-        args.extend(['--exclude-tag', 'wifi_mesh'])
+        args.extend(["--exclude-tag", "wifi_mesh"])
     execute_from_command_line(args)
     sys.exit(
         pytest.main(
-            [os.path.join('openwisp_network_topology', 'tests', 'test_websockets.py')]
+            [os.path.join("openwisp_network_topology", "tests", "test_websockets.py")]
         )
     )
diff --git a/setup.py b/setup.py
index a7b873f1..500368e4 100644
--- a/setup.py
+++ b/setup.py
@@ -9,13 +9,13 @@ def get_install_requires():
     parse requirements.txt, ignore links, exclude comments
     """
     requirements = []
-    for line in open('requirements.txt').readlines():
+    for line in open("requirements.txt").readlines():
         # skip to next iteration if comment or empty line
         if (
-            line.startswith('#')
-            or line == ''
-            or line.startswith('http')
-            or line.startswith('git')
+            line.startswith("#")
+            or line == ""
+            or line.startswith("http")
+            or line.startswith("git")
         ):
             continue
         # add line to requirements
@@ -24,30 +24,30 @@ def get_install_requires():
 
 
 setup(
-    name='openwisp-network-topology',
+    name="openwisp-network-topology",
     version=get_version(),
-    license='BSD-3-Clause',
-    author='OpenWISP',
-    author_email='support@openwisp.io',
-    description='OpenWISP Network Topology',
-    long_description=open('README.rst').read(),
-    url='http://openwisp.org',
-    download_url='https://github.com/openwisp/openwisp-network-topology/releases',
-    platforms=['Platform Independent'],
-    keywords=['django', 'netjson', 'openwrt', 'networking', 'openwisp'],
-    packages=find_packages(exclude=['tests*', 'docs*']),
+    license="BSD-3-Clause",
+    author="OpenWISP",
+    author_email="support@openwisp.io",
+    description="OpenWISP Network Topology",
+    long_description=open("README.rst").read(),
+    url="http://openwisp.org",
+    download_url="https://github.com/openwisp/openwisp-network-topology/releases",
+    platforms=["Platform Independent"],
+    keywords=["django", "netjson", "openwrt", "networking", "openwisp"],
+    packages=find_packages(exclude=["tests*", "docs*"]),
     include_package_data=True,
     zip_safe=False,
     install_requires=get_install_requires(),
     classifiers=[
-        'Development Status :: 5 - Production/Stable ',
-        'Environment :: Web Environment',
-        'Topic :: Internet :: WWW/HTTP',
-        'Topic :: System :: Networking',
-        'Intended Audience :: Developers',
-        'License :: OSI Approved :: BSD License',
-        'Operating System :: OS Independent',
-        'Framework :: Django',
-        'Programming Language :: Python :: 3',
+        "Development Status :: 5 - Production/Stable ",
+        "Environment :: Web Environment",
+        "Topic :: Internet :: WWW/HTTP",
+        "Topic :: System :: Networking",
+        "Intended Audience :: Developers",
+        "License :: OSI Approved :: BSD License",
+        "Operating System :: OS Independent",
+        "Framework :: Django",
+        "Programming Language :: Python :: 3",
     ],
 )
diff --git a/tests/manage.py b/tests/manage.py
index be1b9ff3..33876c7b 100755
--- a/tests/manage.py
+++ b/tests/manage.py
@@ -2,8 +2,8 @@
 import os
 import sys
 
-if __name__ == '__main__':
-    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'openwisp2.settings')
+if __name__ == "__main__":
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "openwisp2.settings")
 
     from django.core.management import execute_from_command_line
 
diff --git a/tests/openwisp2/__init__.py b/tests/openwisp2/__init__.py
index cd042640..370372af 100644
--- a/tests/openwisp2/__init__.py
+++ b/tests/openwisp2/__init__.py
@@ -1,3 +1,3 @@
 from .celery import app as celery_app
 
-__all__ = ['celery_app']
+__all__ = ["celery_app"]
diff --git a/tests/openwisp2/asgi.py b/tests/openwisp2/asgi.py
index 18b6e0c6..4ef2e996 100644
--- a/tests/openwisp2/asgi.py
+++ b/tests/openwisp2/asgi.py
@@ -3,7 +3,7 @@
 from django.conf import settings
 from django.core.asgi import get_asgi_application
 
-if 'openwisp_controller.geo' in settings.INSTALLED_APPS:
+if "openwisp_controller.geo" in settings.INSTALLED_APPS:
     from openwisp_controller.routing import get_routes as get_controller_routes
 else:
     from openwisp_notifications.websockets.routing import (
@@ -22,12 +22,12 @@ def get_controller_routes():
 
 application = ProtocolTypeRouter(
     {
-        'websocket': AuthMiddlewareStack(
+        "websocket": AuthMiddlewareStack(
             URLRouter(
                 openwisp_network_topology.routing.websocket_urlpatterns
                 + get_controller_routes()
             )
         ),
-        'http': get_asgi_application(),
+        "http": get_asgi_application(),
     }
 )
diff --git a/tests/openwisp2/celery.py b/tests/openwisp2/celery.py
index e3c1425d..311028e8 100644
--- a/tests/openwisp2/celery.py
+++ b/tests/openwisp2/celery.py
@@ -2,8 +2,8 @@
 
 from celery import Celery
 
-os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'openwisp2.settings')
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "openwisp2.settings")
 
-app = Celery('openwisp2')
-app.config_from_object('django.conf:settings', namespace='CELERY')
+app = Celery("openwisp2")
+app.config_from_object("django.conf:settings", namespace="CELERY")
 app.autodiscover_tasks()
diff --git a/tests/openwisp2/sample_integration_device/apps.py b/tests/openwisp2/sample_integration_device/apps.py
index 12618cfc..7e63ecc6 100644
--- a/tests/openwisp2/sample_integration_device/apps.py
+++ b/tests/openwisp2/sample_integration_device/apps.py
@@ -4,8 +4,8 @@
 
 
 class OpenwispTopologyDeviceConfig(BaseAppConfig):
-    name = 'openwisp2.sample_integration_device'
-    label = 'sample_integration_device'
+    name = "openwisp2.sample_integration_device"
+    label = "sample_integration_device"
 
 
 del BaseAppConfig
diff --git a/tests/openwisp2/sample_integration_device/celery.py b/tests/openwisp2/sample_integration_device/celery.py
index e3c1425d..311028e8 100644
--- a/tests/openwisp2/sample_integration_device/celery.py
+++ b/tests/openwisp2/sample_integration_device/celery.py
@@ -2,8 +2,8 @@
 
 from celery import Celery
 
-os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'openwisp2.settings')
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "openwisp2.settings")
 
-app = Celery('openwisp2')
-app.config_from_object('django.conf:settings', namespace='CELERY')
+app = Celery("openwisp2")
+app.config_from_object("django.conf:settings", namespace="CELERY")
 app.autodiscover_tasks()
diff --git a/tests/openwisp2/sample_integration_device/migrations/0001_initial.py b/tests/openwisp2/sample_integration_device/migrations/0001_initial.py
index e8e2b589..a32b62ba 100644
--- a/tests/openwisp2/sample_integration_device/migrations/0001_initial.py
+++ b/tests/openwisp2/sample_integration_device/migrations/0001_initial.py
@@ -12,15 +12,15 @@ class Migration(migrations.Migration):
 
     dependencies = [
         migrations.swappable_dependency(settings.CONFIG_DEVICE_MODEL),
-        ('sample_network_topology', '0002_json_properties'),
+        ("sample_network_topology", "0002_json_properties"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='DeviceNode',
+            name="DeviceNode",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -28,29 +28,29 @@ class Migration(migrations.Migration):
                         serialize=False,
                     ),
                 ),
-                ('is_test', models.BooleanField(default=True)),
+                ("is_test", models.BooleanField(default=True)),
                 (
-                    'device',
+                    "device",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
                         to=settings.CONFIG_DEVICE_MODEL,
                     ),
                 ),
                 (
-                    'node',
+                    "node",
                     models.OneToOneField(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to='sample_network_topology.Node',
+                        to="sample_network_topology.Node",
                     ),
                 ),
             ],
-            options={'abstract': False, 'unique_together': {('node', 'device')}},
+            options={"abstract": False, "unique_together": {("node", "device")}},
         ),
         migrations.CreateModel(
-            name='WifiMesh',
+            name="WifiMesh",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -58,10 +58,10 @@ class Migration(migrations.Migration):
                         serialize=False,
                     ),
                 ),
-                ('mesh_id', models.CharField(max_length=32, verbose_name='Mesh ID')),
-                ('is_test', models.BooleanField(default=True)),
+                ("mesh_id", models.CharField(max_length=32, verbose_name="Mesh ID")),
+                ("is_test", models.BooleanField(default=True)),
                 (
-                    'topology',
+                    "topology",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
                         to=settings.TOPOLOGY_TOPOLOGY_MODEL,
@@ -69,7 +69,7 @@ class Migration(migrations.Migration):
                 ),
             ],
             options={
-                'abstract': False,
+                "abstract": False,
             },
         ),
     ]
diff --git a/tests/openwisp2/sample_integration_device/tests.py b/tests/openwisp2/sample_integration_device/tests.py
index 18b4d749..15152a52 100644
--- a/tests/openwisp2/sample_integration_device/tests.py
+++ b/tests/openwisp2/sample_integration_device/tests.py
@@ -10,7 +10,7 @@
     TestMonitoringIntegration as BaseTestMonitoringIntegration,
 )
 
-DeviceNode = swapper.load_model('topology_device', 'DeviceNode')
+DeviceNode = swapper.load_model("topology_device", "DeviceNode")
 
 
 class TestControllerIntegration(BaseTestControllerIntegration):
@@ -23,8 +23,8 @@ class TestMonitoringIntegration(BaseTestMonitoringIntegration):
 
 
 class TestAdmin(BaseTestAdmin):
-    module = 'openwisp2.sample_network_topology'
-    app_label = 'sample_network_topology'
+    module = "openwisp2.sample_network_topology"
+    app_label = "sample_network_topology"
 
 
 del BaseTestControllerIntegration
diff --git a/tests/openwisp2/sample_network_topology/apps.py b/tests/openwisp2/sample_network_topology/apps.py
index f7301cc1..6c621235 100644
--- a/tests/openwisp2/sample_network_topology/apps.py
+++ b/tests/openwisp2/sample_network_topology/apps.py
@@ -2,8 +2,8 @@
 
 
 class SampleNetworkTopologyConfig(OpenwispNetworkTopologyConfig):
-    name = 'openwisp2.sample_network_topology'
-    label = 'sample_network_topology'
+    name = "openwisp2.sample_network_topology"
+    label = "sample_network_topology"
 
 
 del OpenwispNetworkTopologyConfig
diff --git a/tests/openwisp2/sample_network_topology/migrations/0001_initial.py b/tests/openwisp2/sample_network_topology/migrations/0001_initial.py
index ca4c422d..5a90f691 100644
--- a/tests/openwisp2/sample_network_topology/migrations/0001_initial.py
+++ b/tests/openwisp2/sample_network_topology/migrations/0001_initial.py
@@ -22,15 +22,15 @@ class Migration(migrations.Migration):
     initial = True
 
     dependencies = [
-        dependency(*split(settings.AUTH_USER_MODEL), version='0004_default_groups'),
+        dependency(*split(settings.AUTH_USER_MODEL), version="0004_default_groups"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='Topology',
+            name="Topology",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -39,139 +39,139 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('label', models.CharField(max_length=64, verbose_name='label')),
+                ("label", models.CharField(max_length=64, verbose_name="label")),
                 (
-                    'parser',
+                    "parser",
                     models.CharField(
                         choices=[
-                            ('netdiff.OlsrParser', 'OLSRd (txtinfo/jsoninfo)'),
+                            ("netdiff.OlsrParser", "OLSRd (txtinfo/jsoninfo)"),
                             (
-                                'netdiff.BatmanParser',
-                                'batman-advanced (jsondoc/txtinfo)',
+                                "netdiff.BatmanParser",
+                                "batman-advanced (jsondoc/txtinfo)",
                             ),
-                            ('netdiff.BmxParser', 'BMX6 (q6m)'),
-                            ('netdiff.NetJsonParser', 'NetJSON NetworkGraph'),
-                            ('netdiff.CnmlParser', 'CNML 1.0'),
-                            ('netdiff.OpenvpnParser', 'OpenVPN'),
-                            ('netdiff.WireguardParser', 'Wireguard'),
-                            ('netdiff.ZeroTierParser', 'ZeroTier'),
+                            ("netdiff.BmxParser", "BMX6 (q6m)"),
+                            ("netdiff.NetJsonParser", "NetJSON NetworkGraph"),
+                            ("netdiff.CnmlParser", "CNML 1.0"),
+                            ("netdiff.OpenvpnParser", "OpenVPN"),
+                            ("netdiff.WireguardParser", "Wireguard"),
+                            ("netdiff.ZeroTierParser", "ZeroTier"),
                         ],
-                        help_text='Select topology format',
+                        help_text="Select topology format",
                         max_length=128,
-                        verbose_name='format',
+                        verbose_name="format",
                     ),
                 ),
                 (
-                    'strategy',
+                    "strategy",
                     models.CharField(
-                        choices=[('fetch', 'FETCH'), ('receive', 'RECEIVE')],
+                        choices=[("fetch", "FETCH"), ("receive", "RECEIVE")],
                         db_index=True,
-                        default='fetch',
+                        default="fetch",
                         max_length=16,
-                        verbose_name='strategy',
+                        verbose_name="strategy",
                     ),
                 ),
                 (
-                    'url',
+                    "url",
                     models.URLField(
                         blank=True,
-                        help_text='Topology data will be fetched from this URL (FETCH strategy)',
-                        verbose_name='url',
+                        help_text="Topology data will be fetched from this URL (FETCH strategy)",
+                        verbose_name="url",
                     ),
                 ),
                 (
-                    'key',
+                    "key",
                     openwisp_utils.base.KeyField(
                         blank=True,
                         default=openwisp_utils.utils.get_random_key,
-                        help_text='key needed to update topology from nodes ',
+                        help_text="key needed to update topology from nodes ",
                         max_length=64,
                         validators=[
                             django.core.validators.RegexValidator(
-                                re.compile('^[^\\s/\\.]+$'),
-                                code='invalid',
-                                message='This value must not contain spaces, dots or slashes.',
+                                re.compile("^[^\\s/\\.]+$"),
+                                code="invalid",
+                                message="This value must not contain spaces, dots or slashes.",
                             )
                         ],
-                        verbose_name='key',
+                        verbose_name="key",
                     ),
                 ),
                 (
-                    'expiration_time',
+                    "expiration_time",
                     models.PositiveIntegerField(
                         default=0,
                         help_text=(
                             '"Expiration Time" in seconds: setting this to 0 will immediately '
-                            'mark missing links as down; a value higher than 0 will delay marking '
+                            "mark missing links as down; a value higher than 0 will delay marking "
                             'missing links as down until the "modified" field of a link is '
                             'older than "Expiration Time"'
                         ),
-                        verbose_name='expiration time',
+                        verbose_name="expiration time",
                     ),
                 ),
                 (
-                    'published',
+                    "published",
                     models.BooleanField(
                         default=True,
                         help_text="Unpublished topologies won't be updated or shown in the visualizer",
-                        verbose_name='published',
+                        verbose_name="published",
                     ),
                 ),
                 (
-                    'protocol',
+                    "protocol",
                     models.CharField(
-                        blank=True, max_length=64, verbose_name='protocol'
+                        blank=True, max_length=64, verbose_name="protocol"
                     ),
                 ),
                 (
-                    'version',
-                    models.CharField(blank=True, max_length=24, verbose_name='version'),
+                    "version",
+                    models.CharField(blank=True, max_length=24, verbose_name="version"),
                 ),
                 (
-                    'revision',
+                    "revision",
                     models.CharField(
-                        blank=True, max_length=64, verbose_name='revision'
+                        blank=True, max_length=64, verbose_name="revision"
                     ),
                 ),
                 (
-                    'metric',
-                    models.CharField(blank=True, max_length=24, verbose_name='metric'),
+                    "metric",
+                    models.CharField(blank=True, max_length=24, verbose_name="metric"),
                 ),
-                ('details', models.CharField(blank=True, max_length=64, null=True)),
+                ("details", models.CharField(blank=True, max_length=64, null=True)),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         blank=True,
                         null=True,
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
             ],
-            options={'verbose_name_plural': 'topologies', 'abstract': False},
+            options={"verbose_name_plural": "topologies", "abstract": False},
             bases=(openwisp_users.mixins.ValidateOrgMixin, models.Model),
         ),
         migrations.CreateModel(
-            name='Snapshot',
+            name="Snapshot",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -180,40 +180,40 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('data', models.TextField()),
-                ('date', models.DateField(auto_now=True)),
-                ('details', models.CharField(blank=True, max_length=64, null=True)),
+                ("data", models.TextField()),
+                ("date", models.DateField(auto_now=True)),
+                ("details", models.CharField(blank=True, max_length=64, null=True)),
                 (
-                    'topology',
+                    "topology",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to='sample_network_topology.Topology',
+                        to="sample_network_topology.Topology",
                     ),
                 ),
             ],
-            options={'verbose_name_plural': 'snapshots', 'abstract': False},
+            options={"verbose_name_plural": "snapshots", "abstract": False},
             bases=(openwisp_users.mixins.ValidateOrgMixin, models.Model),
         ),
         migrations.CreateModel(
-            name='Node',
+            name="Node",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -222,59 +222,59 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('label', models.CharField(blank=True, max_length=64)),
-                ('addresses', jsonfield.fields.JSONField(default=[])),
+                ("label", models.CharField(blank=True, max_length=64)),
+                ("addresses", jsonfield.fields.JSONField(default=[])),
                 (
-                    'properties',
+                    "properties",
                     jsonfield.fields.JSONField(
                         blank=True,
                         default=dict,
-                        dump_kwargs={'indent': 4},
-                        load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                        dump_kwargs={"indent": 4},
+                        load_kwargs={"object_pairs_hook": collections.OrderedDict},
                     ),
                 ),
-                ('details', models.CharField(blank=True, max_length=64, null=True)),
+                ("details", models.CharField(blank=True, max_length=64, null=True)),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         blank=True,
                         null=True,
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
                 (
-                    'topology',
+                    "topology",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to='sample_network_topology.Topology',
+                        to="sample_network_topology.Topology",
                     ),
                 ),
             ],
-            options={'abstract': False},
+            options={"abstract": False},
             bases=(openwisp_users.mixins.ValidateOrgMixin, models.Model),
         ),
         migrations.CreateModel(
-            name='Link',
+            name="Link",
             fields=[
                 (
-                    'id',
+                    "id",
                     models.UUIDField(
                         default=uuid.uuid4,
                         editable=False,
@@ -283,78 +283,78 @@ class Migration(migrations.Migration):
                     ),
                 ),
                 (
-                    'created',
+                    "created",
                     model_utils.fields.AutoCreatedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='created',
+                        verbose_name="created",
                     ),
                 ),
                 (
-                    'modified',
+                    "modified",
                     model_utils.fields.AutoLastModifiedField(
                         default=django.utils.timezone.now,
                         editable=False,
-                        verbose_name='modified',
+                        verbose_name="modified",
                     ),
                 ),
-                ('cost', models.FloatField()),
-                ('cost_text', models.CharField(blank=True, max_length=24)),
+                ("cost", models.FloatField()),
+                ("cost_text", models.CharField(blank=True, max_length=24)),
                 (
-                    'status',
+                    "status",
                     model_utils.fields.StatusField(
-                        choices=[('up', 'up'), ('down', 'down')],
-                        default='up',
+                        choices=[("up", "up"), ("down", "down")],
+                        default="up",
                         max_length=100,
                         no_check_for_status=True,
                     ),
                 ),
                 (
-                    'properties',
+                    "properties",
                     jsonfield.fields.JSONField(
                         blank=True,
                         default=dict,
-                        dump_kwargs={'indent': 4},
-                        load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                        dump_kwargs={"indent": 4},
+                        load_kwargs={"object_pairs_hook": collections.OrderedDict},
                     ),
                 ),
-                ('status_changed', models.DateTimeField(auto_now=True)),
-                ('details', models.CharField(blank=True, max_length=64, null=True)),
+                ("status_changed", models.DateTimeField(auto_now=True)),
+                ("details", models.CharField(blank=True, max_length=64, null=True)),
                 (
-                    'organization',
+                    "organization",
                     models.ForeignKey(
                         blank=True,
                         null=True,
                         on_delete=django.db.models.deletion.CASCADE,
-                        to=get_model_name('openwisp_users', 'Organization'),
-                        verbose_name='organization',
+                        to=get_model_name("openwisp_users", "Organization"),
+                        verbose_name="organization",
                     ),
                 ),
                 (
-                    'source',
+                    "source",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        related_name='source_link_set',
-                        to='sample_network_topology.Node',
+                        related_name="source_link_set",
+                        to="sample_network_topology.Node",
                     ),
                 ),
                 (
-                    'target',
+                    "target",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        related_name='target_link_set',
-                        to='sample_network_topology.Node',
+                        related_name="target_link_set",
+                        to="sample_network_topology.Node",
                     ),
                 ),
                 (
-                    'topology',
+                    "topology",
                     models.ForeignKey(
                         on_delete=django.db.models.deletion.CASCADE,
-                        to='sample_network_topology.Topology',
+                        to="sample_network_topology.Topology",
                     ),
                 ),
             ],
-            options={'abstract': False},
+            options={"abstract": False},
             bases=(openwisp_users.mixins.ValidateOrgMixin, models.Model),
         ),
     ]
diff --git a/tests/openwisp2/sample_network_topology/migrations/0002_json_properties.py b/tests/openwisp2/sample_network_topology/migrations/0002_json_properties.py
index 8c9a9a54..60576bd1 100644
--- a/tests/openwisp2/sample_network_topology/migrations/0002_json_properties.py
+++ b/tests/openwisp2/sample_network_topology/migrations/0002_json_properties.py
@@ -8,38 +8,38 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('sample_network_topology', '0001_initial')]
+    dependencies = [("sample_network_topology", "0001_initial")]
 
     operations = [
         migrations.AlterField(
-            model_name='link',
-            name='properties',
+            model_name="link",
+            name="properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
             ),
         ),
         migrations.AlterField(
-            model_name='node',
-            name='addresses',
+            model_name="node",
+            name="addresses",
             field=jsonfield.fields.JSONField(blank=True, default=[]),
         ),
         migrations.AlterField(
-            model_name='node',
-            name='properties',
+            model_name="node",
+            name="properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
             ),
         ),
     ]
diff --git a/tests/openwisp2/sample_network_topology/migrations/0003_add_user_defined_properties_field.py b/tests/openwisp2/sample_network_topology/migrations/0003_add_user_defined_properties_field.py
index 4665ada4..cee12e3f 100644
--- a/tests/openwisp2/sample_network_topology/migrations/0003_add_user_defined_properties_field.py
+++ b/tests/openwisp2/sample_network_topology/migrations/0003_add_user_defined_properties_field.py
@@ -8,37 +8,37 @@
 
 
 class Migration(migrations.Migration):
-    dependencies = [('sample_network_topology', '0002_json_properties')]
+    dependencies = [("sample_network_topology", "0002_json_properties")]
 
     operations = [
         migrations.AddField(
-            model_name='link',
-            name='user_properties',
+            model_name="link",
+            name="user_properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                help_text='If you need to add additional data to this link use this field',
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
-                verbose_name='user defined properties',
+                help_text="If you need to add additional data to this link use this field",
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
+                verbose_name="user defined properties",
             ),
         ),
         migrations.AddField(
-            model_name='node',
-            name='user_properties',
+            model_name="node",
+            name="user_properties",
             field=jsonfield.fields.JSONField(
                 blank=True,
                 default=dict,
                 dump_kwargs={
-                    'cls': rest_framework.utils.encoders.JSONEncoder,
-                    'indent': 4,
+                    "cls": rest_framework.utils.encoders.JSONEncoder,
+                    "indent": 4,
                 },
-                help_text='If you need to add additional data to this node use this field',
-                load_kwargs={'object_pairs_hook': collections.OrderedDict},
-                verbose_name='user defined properties',
+                help_text="If you need to add additional data to this node use this field",
+                load_kwargs={"object_pairs_hook": collections.OrderedDict},
+                verbose_name="user defined properties",
             ),
         ),
     ]
diff --git a/tests/openwisp2/sample_network_topology/migrations/0004_default_groups.py b/tests/openwisp2/sample_network_topology/migrations/0004_default_groups.py
index 91c47520..b245f579 100644
--- a/tests/openwisp2/sample_network_topology/migrations/0004_default_groups.py
+++ b/tests/openwisp2/sample_network_topology/migrations/0004_default_groups.py
@@ -14,14 +14,14 @@ def create_default_permissions(apps, schema_editor):
 
 def assign_permissions_to_groups(apps, schema_editor):
     create_default_permissions(apps, schema_editor)
-    operators_and_admin_can_change = ['link', 'node']
-    operators_read_only_admins_manage = ['topology']
-    manage_operations = ['add', 'change', 'delete']
-    Group = apps.get_model('openwisp_users', 'Group')
+    operators_and_admin_can_change = ["link", "node"]
+    operators_read_only_admins_manage = ["topology"]
+    manage_operations = ["add", "change", "delete"]
+    Group = apps.get_model("openwisp_users", "Group")
 
     try:
-        admin = Group.objects.get(name='Administrator')
-        operator = Group.objects.get(name='Operator')
+        admin = Group.objects.get(name="Administrator")
+        operator = Group.objects.get(name="Operator")
     # consider failures custom cases
     # that do not have to be dealt with
     except Group.DoesNotExist:
@@ -30,7 +30,7 @@ def assign_permissions_to_groups(apps, schema_editor):
     for model_name in operators_and_admin_can_change:
         for operation in manage_operations:
             permission = Permission.objects.get(
-                codename='{}_{}'.format(operation, model_name)
+                codename="{}_{}".format(operation, model_name)
             )
             admin.permissions.add(permission.pk)
             operator.permissions.add(permission.pk)
@@ -50,8 +50,8 @@ def assign_permissions_to_groups(apps, schema_editor):
 
 class Migration(migrations.Migration):
     dependencies = [
-        dependency(*split(settings.AUTH_USER_MODEL), version='0004_default_groups'),
-        ('sample_network_topology', '0003_add_user_defined_properties_field'),
+        dependency(*split(settings.AUTH_USER_MODEL), version="0004_default_groups"),
+        ("sample_network_topology", "0003_add_user_defined_properties_field"),
     ]
     operations = [
         migrations.RunPython(
diff --git a/tests/openwisp2/sample_network_topology/tests.py b/tests/openwisp2/sample_network_topology/tests.py
index 876a65fa..c690da89 100644
--- a/tests/openwisp2/sample_network_topology/tests.py
+++ b/tests/openwisp2/sample_network_topology/tests.py
@@ -24,12 +24,12 @@
 
 
 class TestAdmin(BaseTestAdmin):
-    module = 'openwisp2.sample_network_topology'
-    app_label = 'sample_network_topology'
+    module = "openwisp2.sample_network_topology"
+    app_label = "sample_network_topology"
 
 
 class TestMultitenantAdmin(BaseTestMultitenantAdmin):
-    app_label = 'sample_network_topology'
+    app_label = "sample_network_topology"
 
 
 class TestApi(BaseTestApi):
diff --git a/tests/openwisp2/settings.py b/tests/openwisp2/settings.py
index 0872aacb..a1f0b6ac 100644
--- a/tests/openwisp2/settings.py
+++ b/tests/openwisp2/settings.py
@@ -2,172 +2,172 @@
 import sys
 
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-TESTING = 'test' in sys.argv
+TESTING = "test" in sys.argv
 
 
 DEBUG = True
 
-ALLOWED_HOSTS = ['*']
+ALLOWED_HOSTS = ["*"]
 
 DATABASES = {
-    'default': {
-        'ENGINE': 'openwisp_utils.db.backends.spatialite',
-        'NAME': os.path.join(BASE_DIR, 'openwisp_network_topology.db'),
+    "default": {
+        "ENGINE": "openwisp_utils.db.backends.spatialite",
+        "NAME": os.path.join(BASE_DIR, "openwisp_network_topology.db"),
     }
 }
 
 
-SECRET_KEY = '@q4z-^s=mv59#o=uutv4*m=h@)ik4%zp1)-k^_(!_7*x_&+ze$'
+SECRET_KEY = "@q4z-^s=mv59#o=uutv4*m=h@)ik4%zp1)-k^_(!_7*x_&+ze$"
 
 INSTALLED_APPS = [
-    'daphne',
-    'django.contrib.auth',
-    'django.contrib.contenttypes',
-    'django.contrib.sessions',
-    'django.contrib.messages',
-    'django.contrib.staticfiles',
-    'openwisp_utils.admin_theme',
+    "daphne",
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "django.contrib.messages",
+    "django.contrib.staticfiles",
+    "openwisp_utils.admin_theme",
     # all-auth
-    'django.contrib.sites',
-    'openwisp_users.accounts',
-    'allauth',
-    'allauth.account',
-    'allauth.socialaccount',
+    "django.contrib.sites",
+    "openwisp_users.accounts",
+    "allauth",
+    "allauth.account",
+    "allauth.socialaccount",
     # controller  (needed to test integration)
-    'openwisp_controller.pki',
-    'openwisp_controller.config',
-    'openwisp_controller.connection',
-    'openwisp_controller.geo',
-    'openwisp_notifications',
-    'openwisp_ipam',
-    'reversion',
-    'sortedm2m',
-    'flat_json_widget',
+    "openwisp_controller.pki",
+    "openwisp_controller.config",
+    "openwisp_controller.connection",
+    "openwisp_controller.geo",
+    "openwisp_notifications",
+    "openwisp_ipam",
+    "reversion",
+    "sortedm2m",
+    "flat_json_widget",
     # network topology
-    'openwisp_network_topology',
-    'openwisp_network_topology.integrations.device',
-    'openwisp_users',
+    "openwisp_network_topology",
+    "openwisp_network_topology.integrations.device",
+    "openwisp_users",
     # admin
-    'import_export',
-    'admin_auto_filters',
-    'django.contrib.admin',
-    'django.forms',
+    "import_export",
+    "admin_auto_filters",
+    "django.contrib.admin",
+    "django.forms",
     # rest framework
-    'rest_framework',
-    'drf_yasg',
-    'django_filters',
-    'rest_framework.authtoken',
-    'django_extensions',
+    "rest_framework",
+    "drf_yasg",
+    "django_filters",
+    "rest_framework.authtoken",
+    "django_extensions",
     # 'debug_toolbar',
     # channels
-    'channels',
+    "channels",
 ]
 
 
-EXTENDED_APPS = ['django_x509', 'django_loci']
+EXTENDED_APPS = ["django_x509", "django_loci"]
 
-AUTH_USER_MODEL = 'openwisp_users.User'
+AUTH_USER_MODEL = "openwisp_users.User"
 SITE_ID = 1
 
 STATICFILES_FINDERS = [
-    'django.contrib.staticfiles.finders.FileSystemFinder',
-    'django.contrib.staticfiles.finders.AppDirectoriesFinder',
-    'openwisp_utils.staticfiles.DependencyFinder',
+    "django.contrib.staticfiles.finders.FileSystemFinder",
+    "django.contrib.staticfiles.finders.AppDirectoriesFinder",
+    "openwisp_utils.staticfiles.DependencyFinder",
 ]
 
 MIDDLEWARE = [
-    'django.middleware.security.SecurityMiddleware',
-    'django.contrib.sessions.middleware.SessionMiddleware',
-    'django.middleware.common.CommonMiddleware',
-    'django.middleware.csrf.CsrfViewMiddleware',
-    'django.contrib.auth.middleware.AuthenticationMiddleware',
-    'allauth.account.middleware.AccountMiddleware',
-    'django.contrib.messages.middleware.MessageMiddleware',
-    'django.middleware.clickjacking.XFrameOptionsMiddleware',
+    "django.middleware.security.SecurityMiddleware",
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.common.CommonMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "allauth.account.middleware.AccountMiddleware",
+    "django.contrib.messages.middleware.MessageMiddleware",
+    "django.middleware.clickjacking.XFrameOptionsMiddleware",
     # 'debug_toolbar.middleware.DebugToolbarMiddleware',
 ]
 
 # INTERNAL_IPS = ['127.0.0.1']
 
-ROOT_URLCONF = 'openwisp2.urls'
+ROOT_URLCONF = "openwisp2.urls"
 
-ASGI_APPLICATION = 'openwisp2.asgi.application'
+ASGI_APPLICATION = "openwisp2.asgi.application"
 
-CHANNEL_LAYERS = {'default': {'BACKEND': 'channels.layers.InMemoryChannelLayer'}}
-FORM_RENDERER = 'django.forms.renderers.TemplatesSetting'
+CHANNEL_LAYERS = {"default": {"BACKEND": "channels.layers.InMemoryChannelLayer"}}
+FORM_RENDERER = "django.forms.renderers.TemplatesSetting"
 
-LANGUAGE_CODE = 'en-gb'
-TIME_ZONE = 'UTC'
+LANGUAGE_CODE = "en-gb"
+TIME_ZONE = "UTC"
 USE_I18N = True
 USE_L10N = True
 USE_TZ = True
-STATIC_URL = '/static/'
+STATIC_URL = "/static/"
 
 TEMPLATES = [
     {
-        'BACKEND': 'django.template.backends.django.DjangoTemplates',
-        'DIRS': [],
-        'OPTIONS': {
-            'loaders': [
-                'django.template.loaders.filesystem.Loader',
-                'django.template.loaders.app_directories.Loader',
-                'openwisp_utils.loaders.DependencyLoader',
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "OPTIONS": {
+            "loaders": [
+                "django.template.loaders.filesystem.Loader",
+                "django.template.loaders.app_directories.Loader",
+                "openwisp_utils.loaders.DependencyLoader",
             ],
-            'context_processors': [
-                'django.template.context_processors.debug',
-                'django.template.context_processors.request',
-                'django.contrib.auth.context_processors.auth',
-                'django.contrib.messages.context_processors.messages',
-                'openwisp_utils.admin_theme.context_processor.menu_groups',
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.contrib.messages.context_processors.messages",
+                "openwisp_utils.admin_theme.context_processor.menu_groups",
             ],
         },
     }
 ]
 
 LOGGING = {
-    'version': 1,
-    'disable_existing_loggers': False,
-    'filters': {
-        'require_debug_false': {'()': 'django.utils.log.RequireDebugFalse'},
-        'require_debug_true': {'()': 'django.utils.log.RequireDebugTrue'},
+    "version": 1,
+    "disable_existing_loggers": False,
+    "filters": {
+        "require_debug_false": {"()": "django.utils.log.RequireDebugFalse"},
+        "require_debug_true": {"()": "django.utils.log.RequireDebugTrue"},
     },
-    'formatters': {
-        'simple': {'format': '[%(levelname)s] %(message)s'},
-        'verbose': {
-            'format': '\n\n[%(levelname)s %(asctime)s] module: %(module)s, process: %(process)d, thread: %(thread)d\n%(message)s'
+    "formatters": {
+        "simple": {"format": "[%(levelname)s] %(message)s"},
+        "verbose": {
+            "format": "\n\n[%(levelname)s %(asctime)s] module: %(module)s, process: %(process)d, thread: %(thread)d\n%(message)s"
         },
     },
-    'handlers': {
-        'console': {
-            'level': 'DEBUG',
-            'class': 'logging.StreamHandler',
-            'filters': ['require_debug_true'],
-            'formatter': 'simple',
+    "handlers": {
+        "console": {
+            "level": "DEBUG",
+            "class": "logging.StreamHandler",
+            "filters": ["require_debug_true"],
+            "formatter": "simple",
         },
-        'mail_admins': {
-            'level': 'ERROR',
-            'filters': ['require_debug_false'],
-            'class': 'django.utils.log.AdminEmailHandler',
+        "mail_admins": {
+            "level": "ERROR",
+            "filters": ["require_debug_false"],
+            "class": "django.utils.log.AdminEmailHandler",
         },
-        'main_log': {
-            'level': 'ERROR',
-            'class': 'logging.handlers.RotatingFileHandler',
-            'formatter': 'verbose',
-            'filename': os.path.join(BASE_DIR, 'error.log'),
-            'maxBytes': 5242880.0,
-            'backupCount': 3,
+        "main_log": {
+            "level": "ERROR",
+            "class": "logging.handlers.RotatingFileHandler",
+            "formatter": "verbose",
+            "filename": os.path.join(BASE_DIR, "error.log"),
+            "maxBytes": 5242880.0,
+            "backupCount": 3,
         },
     },
-    'root': {'level': 'INFO', 'handlers': ['main_log', 'console', 'mail_admins']},
-    'loggers': {'py.warnings': {'handlers': ['console']}},
+    "root": {"level": "INFO", "handlers": ["main_log", "console", "mail_admins"]},
+    "loggers": {"py.warnings": {"handlers": ["console"]}},
 }
 
-TEST_RUNNER = 'openwisp_network_topology.tests.utils.LoggingDisabledTestRunner'
+TEST_RUNNER = "openwisp_network_topology.tests.utils.LoggingDisabledTestRunner"
 
 # during development only
-EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
+EMAIL_BACKEND = "django.core.mail.backends.console.EmailBackend"
 
-LOGIN_REDIRECT_URL = 'admin:index'
+LOGIN_REDIRECT_URL = "admin:index"
 ACCOUNT_LOGOUT_REDIRECT_URL = LOGIN_REDIRECT_URL
 
 OPENWISP_ORGANIZATION_USER_ADMIN = True
@@ -179,63 +179,63 @@
 # and should not be used in a production environment
 CELERY_TASK_ALWAYS_EAGER = True
 CELERY_TASK_EAGER_PROPAGATES = True
-CELERY_BROKER_URL = 'memory://'
+CELERY_BROKER_URL = "memory://"
 
-if not TESTING and any(['shell' in sys.argv, 'shell_plus' in sys.argv]):
+if not TESTING and any(["shell" in sys.argv, "shell_plus" in sys.argv]):
     LOGGING.update(
         {
-            'loggers': {
-                'django.db.backends': {
-                    'handlers': ['console'],
-                    'level': 'DEBUG',
-                    'propagate': False,
+            "loggers": {
+                "django.db.backends": {
+                    "handlers": ["console"],
+                    "level": "DEBUG",
+                    "propagate": False,
                 }
             }
         }
     )
 
 # Avoid adding unnecessary dependency to speedup tests.
-if not TESTING or (TESTING and os.environ.get('WIFI_MESH', False)):
+if not TESTING or (TESTING and os.environ.get("WIFI_MESH", False)):
     OPENWISP_NETWORK_TOPOLOGY_WIFI_MESH_INTEGRATION = True
-    openwisp_ipam_index = INSTALLED_APPS.index('openwisp_ipam')
-    INSTALLED_APPS.insert(openwisp_ipam_index, 'leaflet')
-    INSTALLED_APPS.insert(openwisp_ipam_index, 'nested_admin')
-    INSTALLED_APPS.insert(openwisp_ipam_index, 'openwisp_monitoring.check')
-    INSTALLED_APPS.insert(openwisp_ipam_index, 'openwisp_monitoring.device')
-    INSTALLED_APPS.insert(openwisp_ipam_index, 'openwisp_monitoring.monitoring')
+    openwisp_ipam_index = INSTALLED_APPS.index("openwisp_ipam")
+    INSTALLED_APPS.insert(openwisp_ipam_index, "leaflet")
+    INSTALLED_APPS.insert(openwisp_ipam_index, "nested_admin")
+    INSTALLED_APPS.insert(openwisp_ipam_index, "openwisp_monitoring.check")
+    INSTALLED_APPS.insert(openwisp_ipam_index, "openwisp_monitoring.device")
+    INSTALLED_APPS.insert(openwisp_ipam_index, "openwisp_monitoring.monitoring")
     TIMESERIES_DATABASE = {
-        'BACKEND': 'openwisp_monitoring.db.backends.influxdb',
-        'USER': 'openwisp',
-        'PASSWORD': 'openwisp',
-        'NAME': 'openwisp2',
-        'HOST': os.getenv('INFLUXDB_HOST', 'localhost'),
-        'PORT': '8086',
+        "BACKEND": "openwisp_monitoring.db.backends.influxdb",
+        "USER": "openwisp",
+        "PASSWORD": "openwisp",
+        "NAME": "openwisp2",
+        "HOST": os.getenv("INFLUXDB_HOST", "localhost"),
+        "PORT": "8086",
     }
     OPENWISP_MONITORING_MAC_VENDOR_DETECTION = False
     CACHES = {
-        'default': {
-            'BACKEND': 'django_redis.cache.RedisCache',
-            'LOCATION': 'redis://localhost/9',
-            'OPTIONS': {
-                'CLIENT_CLASS': 'django_redis.client.DefaultClient',
+        "default": {
+            "BACKEND": "django_redis.cache.RedisCache",
+            "LOCATION": "redis://localhost/9",
+            "OPTIONS": {
+                "CLIENT_CLASS": "django_redis.client.DefaultClient",
             },
         }
     }
 
-if os.environ.get('SAMPLE_APP', False):
-    INSTALLED_APPS.remove('openwisp_network_topology')
-    INSTALLED_APPS.remove('openwisp_network_topology.integrations.device')
-    EXTENDED_APPS.append('openwisp_network_topology')
+if os.environ.get("SAMPLE_APP", False):
+    INSTALLED_APPS.remove("openwisp_network_topology")
+    INSTALLED_APPS.remove("openwisp_network_topology.integrations.device")
+    EXTENDED_APPS.append("openwisp_network_topology")
     INSTALLED_APPS += [
-        'openwisp2.sample_network_topology',
-        'openwisp2.sample_integration_device',
+        "openwisp2.sample_network_topology",
+        "openwisp2.sample_integration_device",
     ]
-    TOPOLOGY_LINK_MODEL = 'sample_network_topology.Link'
-    TOPOLOGY_NODE_MODEL = 'sample_network_topology.Node'
-    TOPOLOGY_SNAPSHOT_MODEL = 'sample_network_topology.Snapshot'
-    TOPOLOGY_TOPOLOGY_MODEL = 'sample_network_topology.Topology'
-    TOPOLOGY_DEVICE_DEVICENODE_MODEL = 'sample_integration_device.DeviceNode'
-    TOPOLOGY_DEVICE_WIFIMESH_MODEL = 'sample_integration_device.WifiMesh'
+    TOPOLOGY_LINK_MODEL = "sample_network_topology.Link"
+    TOPOLOGY_NODE_MODEL = "sample_network_topology.Node"
+    TOPOLOGY_SNAPSHOT_MODEL = "sample_network_topology.Snapshot"
+    TOPOLOGY_TOPOLOGY_MODEL = "sample_network_topology.Topology"
+    TOPOLOGY_DEVICE_DEVICENODE_MODEL = "sample_integration_device.DeviceNode"
+    TOPOLOGY_DEVICE_WIFIMESH_MODEL = "sample_integration_device.WifiMesh"
 
 # local settings must be imported before test runner otherwise they'll be ignored
 try:
diff --git a/tests/openwisp2/urls.py b/tests/openwisp2/urls.py
index b387351a..70f23b33 100644
--- a/tests/openwisp2/urls.py
+++ b/tests/openwisp2/urls.py
@@ -9,27 +9,27 @@
 
 urlpatterns = []
 
-if os.environ.get('SAMPLE_APP', False):
+if os.environ.get("SAMPLE_APP", False):
     from openwisp_network_topology.utils import get_visualizer_urls
 
     from .sample_network_topology.visualizer import views
 
-    urlpatterns += [path('topology/', include(get_visualizer_urls(views)))]
+    urlpatterns += [path("topology/", include(get_visualizer_urls(views)))]
 
 urlpatterns += [
-    path('', include('openwisp_network_topology.urls')),
+    path("", include("openwisp_network_topology.urls")),
     # needed to test integrations
-    path('', include('openwisp_controller.urls')),
-    path('admin/', admin.site.urls),
-    path('api/v1/', include('openwisp_utils.api.urls')),
-    path('api/v1/', include(get_api_urls())),
+    path("", include("openwisp_controller.urls")),
+    path("admin/", admin.site.urls),
+    path("api/v1/", include("openwisp_utils.api.urls")),
+    path("api/v1/", include(get_api_urls())),
 ]
 
 urlpatterns += staticfiles_urlpatterns()
-if 'openwisp_monitoring.monitoring' in settings.INSTALLED_APPS:
-    urlpatterns.append(path('', include('openwisp_monitoring.urls')))
+if "openwisp_monitoring.monitoring" in settings.INSTALLED_APPS:
+    urlpatterns.append(path("", include("openwisp_monitoring.urls")))
 
-if settings.DEBUG and 'debug_toolbar' in settings.INSTALLED_APPS:
+if settings.DEBUG and "debug_toolbar" in settings.INSTALLED_APPS:
     import debug_toolbar
 
-    urlpatterns += [path('__debug__/', include(debug_toolbar.urls))]
+    urlpatterns += [path("__debug__/", include(debug_toolbar.urls))]