code: func (u *User) String() string {
  	if u.UserName != "" {
  		return u.UserName
  	}
  
  	name := u.FirstName
  	if u.LastName != "" {
  		name += " " + u.LastName
  	}
  
  	return name
  }
docs: // String displays a simple text version of a user.
  //
  // It is normally a user's username, but falls back to a first/last
  // name as available.