          """
          m2m_data = {}
          related_data = {}
          nested_forward_relations = {}
          removed_relations = []
          meta = self.opts.model._meta
  
          # Reverse fk or one-to-one relations
          for (obj, model) in meta.get_all_related_objects_with_model():
              field_name = obj.field.related_query_name()
 
</s> remove         instance._removed_relations = removed_relations
 </s> add  </s> remove                         self._deleted = identity_to_objects.values()
 </s> add                         ret._deleted = identity_to_objects.values() </s> remove         # Deleted related objects
        if self._deleted:
            removed_relations = list(self._deleted)

 </s> add  </s> remove         self._deleted = None
 </s> add  </s> remove                 ret = []
 </s> add                 ret = RelationsList()
          """
          m2m_data = {}
          related_data = {}
          nested_forward_relations = {}

          meta = self.opts.model._meta
  
          # Reverse fk or one-to-one relations
          for (obj, model) in meta.get_all_related_objects_with_model():
              field_name = obj.field.related_query_name()
keep keep keep keep replace keep keep keep keep keep
 Fix model serializer nestesd delete behavior 
rest_framework/serializers.py