code: func (bot *BotAPI) sendFile(config Fileable) (Message, error) {
  	if config.useExistingFile() {
  		return bot.sendExisting(config.method(), config)
  	}
  
  	return bot.uploadAndSend(config.method(), config)
  }
docs: // sendFile determines if the file is using an existing file or uploading
  // a new file, then sends it as needed.