diff --git a/climetlab.code-workspace b/climetlab.code-workspace
index c4b8ca74..9ab1f7b1 100644
--- a/climetlab.code-workspace
+++ b/climetlab.code-workspace
@@ -14,6 +14,9 @@
 		},
 		{
 			"path": "../magics-python"
+		},
+		{
+			"path": "../magics-test"
 		}
 	],
 	"settings": {
diff --git a/climetlab/sources/multi.py b/climetlab/sources/multi.py
index 1817710a..cf8975ca 100644
--- a/climetlab/sources/multi.py
+++ b/climetlab/sources/multi.py
@@ -21,15 +21,15 @@ def __init__(self, *sources):
         self.sources = sources
         self._lengths = [None] * len(sources)
 
-    def mutate(self):
-        if len(self.sources) == 1:
-            return self.sources[0].mutate()
+    # def not_yet_mutate(self):
+    #     if len(self.sources) == 1:
+    #         return self.sources[0].mutate()
 
-        t = type(self.sources[0])
-        if all(type(s) == t for s in self.sources):
-            return t.multi_merge(self.sources).mutate()
+    #     t = type(self.sources[0])
+    #     if all(type(s) == t for s in self.sources):
+    #         return t.multi_merge(self.sources).mutate()
 
-        return self
+    #     return self
 
     def _set_dataset(self, dataset):
         super()._set_dataset(dataset)
diff --git a/test.py b/test.py
index 3d054703..87539988 100644
--- a/test.py
+++ b/test.py
@@ -2,16 +2,6 @@
 # coding: utf-8
 
 # In[73]:
+import climetlab as cml
 
-
-import cfgrib
-import xarray as xr
-
-from climetlab import load_source
-from climetlab.sources.readers.grib import FieldSetIndex
-
-source = load_source("file", "docs/examples/test.grib")
-
-store = xr.backends.CfGribDataStore(FieldSetIndex(source))
-
-d = xr.open_dataset(store, engine="cfgrib")
+ds = cml.load_dataset("era5-temperature", period=(1979, 1982), domain="France", time=12)