code: def get_bar_config(self, bar_id=None):
          
          if not bar_id:
              bar_config_list = self.get_bar_config_list()
              if not bar_config_list:
                  return None
              bar_id = bar_config_list[0]
  
          data = self.message(MessageType.GET_BAR_CONFIG, bar_id)
          return json.loads(data, object_hook=BarConfigReply)
docs: Get the configuration of a single bar. Defaults to the first if none is
          specified. Use :meth:`get_bar_config_list` to obtain a list of valid
          IDs.
  
          :rtype: BarConfigReply