code: def parent(self):
          
          if len(self._path) == 1:
              return None
          else:
              parent_path = self._path[:-1]
          return self._client.document(*parent_path)
docs: Document that owns the current collection.
  
          Returns:
              Optional[~.firestore_v1beta1.document.DocumentReference]: The
              parent document, if the current collection is not a
              top-level collection.