Send Message, Log and Activity Buttons in form views

First we have to inherit mail.thread and mail.activity.mixin module in the specific model inside the class. Here in the patient.py file.
```
_inherit = ['mail.thread', 'mail.activity.mixin']
```
Add inherited module name in the depends in __manifest__.py.
```
'depends': ['mail']
```
Add this code to the patient_view.xml inside the form tag and after the sheet tag. file for viewing chatter options. It will integrate messaging features and activity to the model. It will look like this.
```
<div class="oe_chatter">
    <field name="message_follower_ids"/>
    <field name="activity_ids"/>
    <field name="message_ids"/>
</div>
```
In the Schedule activity we can schedule based on different activities like Todo, Call etc. Explore this by your own.
Check this code examples
Task
- Try to add chatter in doctor and appointment model.

Track field value changes and log in chatter

For tracking field value changes we have to add an attribute named tracking=True in that field in .py file. Example:
```
name = fields.Char(string='Patient Name', required=True, tracking=True)
```
And it will save a log in the chatter and also who have changed the value. Try to add tracking in other fields in doctor.py, patient.py and appointment.py file.