code: def _get_entity(self):
          
          if self._is_ndb():
              return self._model.get_by_id(self._key_name)
          else:
              return self._model.get_by_key_name(self._key_name)
docs: Retrieve entity from datastore.
  
          Uses a different model method for db or ndb models.
  
          Returns:
              Instance of the model corresponding to the current storage object
              and stored using the key name of the storage object.