code: func (bot *BotAPI) GetChatMembersCount(config ChatConfig) (int, error) {
  	v := url.Values{}
  
  	if config.SuperGroupUsername == "" {
  		v.Add("chat_id", strconv.FormatInt(config.ChatID, 10))
  	} else {
  		v.Add("chat_id", config.SuperGroupUsername)
  	}
  
  	resp, err := bot.MakeRequest("getChatMembersCount", v)
  	if err != nil {
  		return -1, err
  	}
  
  	var count int
  	err = json.Unmarshal(resp.Result, &count)
  
  	bot.debugLog("getChatMembersCount", v, count)
  
  	return count, err
  }
docs: // GetChatMembersCount gets the number of users in a chat.