code: func (u *UserCommand) PrintSignupURL(client auth.ClientI, token string, ttl time.Duration, format string) error {
  	signupURL, proxyHost := web.CreateSignupLink(client, token)
  
  	if format == teleport.Text {
  		fmt.Printf("Signup token has been created and is valid for %v hours. Share this URL with the user:\n%v\n\n",
  			int(ttl/time.Hour), signupURL)
  		fmt.Printf("NOTE: Make sure %v points at a Teleport proxy which users can access.\n", proxyHost)
  	} else {
  		out, err := json.MarshalIndent(services.NewInviteToken(token, signupURL, time.Now().Add(ttl).UTC()), "", "  ")
  		if err != nil {
  			return trace.Wrap(err, "failed to marshal signup infos")
  		}
  		fmt.Printf(string(out))
  	}
  	return nil
  }
docs: // PrintSignupURL prints signup URL