code: func (u *UserCommand) TryRun(cmd string, client auth.ClientI) (match bool, err error) {
  	switch cmd {
  	case u.userAdd.FullCommand():
  		err = u.Add(client)
  	case u.userUpdate.FullCommand():
  		err = u.Update(client)
  	case u.userList.FullCommand():
  		err = u.List(client)
  	case u.userDelete.FullCommand():
  		err = u.Delete(client)
  	default:
  		return false, nil
  	}
  	return true, trace.Wrap(err)
  }
docs: // TryRun takes the CLI command as an argument (like "users add") and executes it.