code: func (fb *Firebase) Ref(path string) (*Firebase, error) {
  	newFB := fb.copy()
  	parsedURL, err := _url.Parse(fb.url)
  	if err != nil {
  		return newFB, err
  	}
  	newFB.url = parsedURL.Scheme + "://" + parsedURL.Host + "/" + strings.Trim(path, "/")
  	return newFB, nil
  }
docs: // Ref returns a copy of an existing Firebase reference with a new path.