code: func LockUser(name string) error {
  	shadow, err := LookupShadow(name)
  	if err != nil {
  		return err
  	}
  
  	if shadow.password[0] != _LOCK_CHAR {
  		shadow.password = string(_LOCK_CHAR) + shadow.password
  		return edit(name, shadow)
  	}
  	return nil
  }
docs: // == Locking
  // LockUser locks the passwd of the given user.