code: func (m *subMenu) Item(indexes ...int) (mi *MenuItem, err error) {
  	var is = m
  	if len(indexes) > 1 {
  		var s *SubMenu
  		if s, err = m.SubMenu(indexes[:len(indexes)-1]...); err != nil {
  			return
  		}
  		is = s.subMenu
  	}
  	var index = indexes[len(indexes)-1]
  	if index >= len(is.items) {
  		return nil, fmt.Errorf("Submenu has %d items, invalid index %d", len(is.items), index)
  	}
  	mi = is.items[index]
  	return
  }
docs: // Item returns the item at the specified indexes