code: func CommandName(fileName string) (commandName string, err error) {
  	fileType := path.Ext(fileName)
  	if fileType == ".mp3" {
  		return "mpg123", nil
  	} else if fileType == ".wav" {
  		return "aplay", nil
  	} else {
  		return "", errors.New("Unknown filetype for audio file.")
  	}
  }
docs: // CommandName defines the playback command for a sound and accepts:
  //
  //  string: The filename of the audio that needs playback