def _backend_worker(self):
        """
        Backend worker queue thread

        Returns:
            None

        """
        while not self.backend_stop_event.isSet():
            cmd = self.backend_queue.get()
            if cmd is None:
                break
            self.safe_send(cmd)

        Backend worker queue thread

        Returns:
            None

        
airtest/core/android/touch_methods/base_touch.py