code: func NewSpinner(message string, chars []string, delay time.Duration, writer io.Writer) Spinner {
  	return Spinner{
  		message: message,
  		chars:   chars,
  		delay:   delay,
  		writer:  writer,
  
  		active:   false,
  		stopChan: make(chan bool),
  	}
  }
docs: // NewSpinner ...