api.go
func (api *TelegramBotAPI) Close() {
	select {
	case <-api.closed:
		return
	default:
	}
	close(api.closed)
	api.wg.Wait()
}
func (api *TelegramBotAPI) Close() {
	select {
	case <-api.closed:
		return
	default:
	}
	close(api.closed)
	api.wg.Wait()
}
// Close shuts down this client.
// Until Close returns, new updates and errors will be put into the
// respective channels.
// Note that, if no updates are received, this function may block for up to
// one minute, which is the time interval
// for long polling.