code: func (menu *Menu) AddSeparator() {
  	command := Command{
  		Method: "add_separator",
  	}
  	menuItem := MenuItem{
  		Type:   "separator",
  		Parent: menu,
  	}
  	menu.Items = append(menu.Items, &menuItem)
  	menu.CallWhenReady(&command)
  }
docs: /*
  AddSeperator adds a Seperator Item to both the internal representation of menu and the external representation of menu.
  */