              removed_relations = list(self._deleted)
  
          if instance is not None:
              instance.update(attrs)
              instance._removed_relations = removed_relations
              return instance
          return attrs
  
      def to_native(self, obj):
          """
 
</s> remove         removed_relations = []

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

 </s> add  </s> remove         instance._removed_relations = removed_relations
 </s> add  </s> remove         # Deleted related objects
        if self._deleted:
            removed_relations = list(self._deleted)

 </s> add  </s> remove         if self.allow_add_remove and hasattr(obj, '_removed_relations'):
            [self.delete_object(item) for item in obj._removed_relations]

 </s> add  </s> remove         self._deleted = None
 </s> add 
              removed_relations = list(self._deleted)
  
          if instance is not None:
              instance.update(attrs)

              return instance
          return attrs
  
      def to_native(self, obj):
          """
keep keep keep keep replace keep keep keep keep keep
 Fix model serializer nestesd delete behavior 
rest_framework/serializers.py