code: def set_sound_mode(self, sound_mode):
          
          if sound_mode == ALL_ZONE_STEREO:
              if self._set_all_zone_stereo(True):
                  self._sound_mode_raw = ALL_ZONE_STEREO
                  return True
              else:
                  return False
          if self._sound_mode_raw == ALL_ZONE_STEREO:
              if not self._set_all_zone_stereo(False):
                  return False
          # For selection of sound mode other names then at receiving sound modes
          # have to be used
          # Therefore source mapping is needed to get sound_mode
          # Create command URL and send command via HTTP GET
          command_url = self._urls.command_sel_sound_mode + sound_mode
          # sent command
          try:
              if self.send_get_command(command_url):
                  self._sound_mode_raw = self._sound_mode_dict[sound_mode][0]
                  return True
              else:
                  return False
          except requests.exceptions.RequestException:
              _LOGGER.error("Connection error: sound mode function %s not set.",
                            sound_mode)
              return False
docs: Set sound_mode of device.
  
          Valid values depend on the device and should be taken from
          "sound_mode_list".
          Return "True" on success and "False" on fail.