code: func NewSystemUser(name, homeDir string, gid int) *User {
  	return &User{
  		Name:  name,
  		Dir:   homeDir,
  		Shell: "/bin/false",
  		UID:   -1,
  		GID:   gid,
  
  		addSystemUser: true,
  	}
  }
docs: // NewSystemUser returns a new system user.