code: def get_volume(self, channel=None):
          
  
          if channel is None:
              channel = self._get_channel()
  
          out = check_output(['amixer', 'get', channel]).decode()
          m = re.search(r'\[(?P<volume>\d+)%\]', out)
          if m:
              return int(m.group('volume'))
          else:
              raise Exception('Failed to parse output of `amixer get {}`'.format(channel))
docs: Gets the current sound volume by parsing the output of
          ``amixer get <channel>``.
          If the channel is not specified, it tries to determine the default one
          by running ``amixer scontrols``. If that fails as well, it uses the
          ``Playback`` channel, as that is the only channel on the EV3.