code: def __write_error(self, status_code, error_message=None):
      
      if error_message is None:
        error_message = httplib.responses[status_code]
      status = '%d %s' % (status_code, httplib.responses[status_code])
      message = EndpointsErrorMessage(
          state=EndpointsErrorMessage.State.APPLICATION_ERROR,
          error_message=error_message)
      return status, self.__PROTOJSON.encode_message(message)
docs: Return the HTTP status line and body for a given error code and message.
  
      Args:
        status_code: HTTP status code to be returned.
        error_message: Error message to be returned.
  
      Returns:
        Tuple (http_status, body):
          http_status: HTTP status line, e.g. 200 OK.
          body: Body of the HTTP request.