def volume_down(self):
        if self.volume_level > 0:
            self.set_volume_level(max(0, self.volume_level - .1))
Callback for Connection object to send an error message to the robot
dataset/ETHPy150Open home-assistant/home-assistant/homeassistant/components/media_player/__init__.py/MediaPlayerDevice.volume_down--crossover with--dataset/ETHPy150Open rapyuta/rce/rce-comm/rce/comm/server.py/RobotWebSocketProtocol.sendErrorMessage