code: func NewBotAPIWithClient(token string, client *http.Client) (*BotAPI, error) {
  	bot := &BotAPI{
  		Token:  token,
  		Client: client,
  		Buffer: 100,
  		shutdownChannel: make(chan interface{}),
  	}
  
  	self, err := bot.GetMe()
  	if err != nil {
  		return nil, err
  	}
  
  	bot.Self = self
  
  	return bot, nil
  }
docs: // NewBotAPIWithClient creates a new BotAPI instance
  // and allows you to pass a http.Client.
  //
  // It requires a token, provided by @BotFather on Telegram.