docs: def save_form(self, form):
          """
          Save a valid form. If there is a parent attribute,
          this will make sure that the parent object is added
          to the saved object. Either as a relationship before
          saving or in the case of many to many relations after
          saving. Any forced instance values are set as well.
  
          Returns the saved object.
          """
  
          # Add any force_instance_values
          force = self.get_force_instance_values()
          if force:
              for k, v in force.items():
                  setattr(form.instance, k, v)
  
          # Are we adding to an attr or manager
          should_add = False
          if self.parent_object:
              m2ms = [f.name for f in form.instance._meta.many_to_many]
              m2ms.extend(
                  [f.field.rel.related_name for f in
                      [
                          f for f in form.instance._meta.get_fields(include_hidden=True)
                          if f.many_to_many and f.auto_created
                      ]
                  ]
              )
  
              if self.parent_field in m2ms:
                  should_add = True
              else:
                  try:
                      form.instance._meta.get_field(self.parent_field)
                      setattr(form.instance, self.parent_field,
                              self.parent_object)
                  except FieldDoesNotExist:
                      pass
  
          obj = form.save()
          # Do we need to add this to a m2m
          if should_add:
              getattr(obj, self.parent_field).add(self.parent_object)
  
          return obj