code: func (ch *CredHub) AuthURL() (string, error) {
  	if ch.authURL != nil {
  		return ch.authURL.String(), nil
  	}
  
  	info, err := ch.Info()
  
  	if err != nil {
  		return "", err
  	}
  
  	authURL := info.AuthServer.URL
  
  	if authURL == "" {
  		return "", errors.New("AuthURL not found")
  	}
  
  	return authURL, nil
  }
docs: // AuthURL returns the targeted CredHub server's trusted authentication server URL.