                                    'Use the `many=True` flag when instantiating the serializer.',
                                    PendingDeprecationWarning, stacklevel=3)
  
              if many:
                  ret = []
                  errors = []
                  update = self.object is not None
  
                  if update:
                      # If this is a bulk update we need to map all the objects
 
</s> remove         self._deleted = None
 </s> add  </s> remove         removed_relations = []

        # Deleted related objects
        if self._deleted:
            removed_relations = list(self._deleted)

 </s> add  </s> remove                         self._deleted = identity_to_objects.values()
 </s> add                         ret._deleted = identity_to_objects.values() </s> remove         instance._removed_relations = removed_relations
 </s> add 
                ret = RelationsList()
                                    'Use the `many=True` flag when instantiating the serializer.',
                                    PendingDeprecationWarning, stacklevel=3)
  
              if many:
                ret = RelationsList()
                  errors = []
                  update = self.object is not None
  
                  if update:
                      # If this is a bulk update we need to map all the objects
keep keep keep keep replace keep keep keep keep keep
 Fix model serializer nestesd delete behavior 
rest_framework/serializers.py