code: def set_volume(self, percent, update_group=True):
          
          if percent not in range(0, 101):
              raise ValueError('Volume percent out of range')
          new_volume = self._client['config']['volume']
          new_volume['percent'] = percent
          self._client['config']['volume']['percent'] = percent
          yield from self._server.client_volume(self.identifier, new_volume)
          if update_group:
              self._server.group(self.group.identifier).callback()
          _LOGGER.info('set volume to %s on %s', percent, self.friendly_name)
docs: Set client volume percent.