def stop(self):
        """
        Remove all log observers previously set up by L{AppLogger.start}.
        """
        logger._loggerFor(self).info("Server Shut Down.")
        if self._observer is not None:
            logger.globalLogPublisher.removeObserver(self._observer)
            self._observer = None

        Remove all log observers previously set up by L{AppLogger.start}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/app.py