code: def _set_keys_for_save_query(self, query):
          
          query.where(self._morph_type, self._morph_class)
  
          return super(MorphPivot, self)._set_keys_for_save_query(query)
docs: Set the keys for a save update query.
  
          :param query: A Builder instance
          :type query: eloquent.orm.Builder
  
          :return: The Builder instance
          :rtype: eloquent.orm.Builder