Cleanup routine: remove the pid file and save the pickle database

def cleanup(self):
        """Cleanup routine: remove the pid file and save the pickle database"""
        try:
            os.remove(self.pid_file)
        except OSError as exc:
            logger.critical("Could not remove pid_file: %s", exc)

        # Save the final status of the flow.
        self.flow.pickle_dump()