add an item to a submenu using a menu path array

def add_to_submenu(self, submenu_path, item):
        '''add an item to a submenu using a menu path array'''
        if len(submenu_path) == 0:
            self.add(item)
            return
        for m in self.items:
            if isinstance(m, MPMenuSubMenu) and submenu_path[0] == m.name:
                m.add_to_submenu(submenu_path[1:], item)
                return
        self.add(MPMenuSubMenu(submenu_path[0], []))
        self.add_to_submenu(submenu_path, item)