Django: MakeValid not working for a single object : I'm trying to use `MakeValid` for fixing my geometry fields. I can make it work by getting and updating in single line:

    from django.contrib.gis.db.models.functions import MakeValid

    MyModel.objects.filter(id=<id>).update(polygon=MakeValid('polygon'))

but for some cases, I've to update `polygon` of a single `object` already existing in function (means I need not to do `.filter`/`.get`) which gives me an error.

    // np is an object of MyModel which has a field 'polygon'
    np.polygon = MakeValid(np.polygon)
    // np.save()
    TypeError: Cannot set MyModel SpatialProxy (MULTIPOLYGON) with value of type: <class 'django.contrib.gis.db.models.functions.MakeValid'>

What am I doing wrong?
