def OnTimeout(self, arg, parameters):  # pylint: disable=unused-argument
    """This function is called upon timeout without timely callback.

    Args:
      arg (input_type): The input of the pipeline.
      parameters (dict): A mapping from names to string values of the saved
          parameters.
    """
    logging.error('%s.OnTimeout called with %s after %s seconds',
                  type(self).__name__, parameters, self.TimeoutSeconds())

this method introduces arg as input, but never used it, thus causing pylint errors.