@classmethod<EOL><INDENT>def _lookup_model(cls, kind, default_model=None):<DEDENT>
modelclass = cls._kind_map.get(kind, default_model)<EOL>if modelclass is None:<EOL><INDENT>raise KindError(<EOL>"<STR_LIT>" %<EOL>kind)<EOL><DEDENT>return modelclass<EOL>
Get the model class for the kind.

        Args:
          kind: A string representing the name of the kind to lookup.
          default_model: The model class to use if the kind can't be found.

        Returns:
          The model class for the requested kind.
        Raises:
          KindError: The kind was not found and no default_model was provided.