code: func (sp *Spec) Args() []string {
  	var args []string
  	if sp.User != "" {
  		args = append(args, "-l", sp.User)
  	}
  	if sp.Port != "" {
  		args = append(args, "-p", sp.Port)
  	}
  	args = append(args, sp.Host)
  	return args
  }
docs: // Args returns args except "ssh" itself and "-- ..."