code: func AddUser(name string, gid int) (uid int, err error) {
  	s := NewShadow(name)
  	if err = s.Add(nil); err != nil {
  		return
  	}
  
  	return NewUser(name, gid).Add()
  }
docs: // == Editing
  //
  // AddUser adds an user to both user and shadow files.