navigation_builder_use.dart

var navItems = <NavigationItem>[
    new NavigationItem(
        icon: const Icon(Icons.home),
        title: 'Home',
        onTap: () => Navigator.pushNamed(context, '/')),
    new NavigationItem(
        icon: const Icon(Icons.change_history),
        title: 'Hidden',
        onTap: () => Navigator.pushNamed(context, '/hidden')),
  ];
  var navMenu = new NavigationMenu(items: navItems);
  return new Scaffold(
    ...
    drawer: navMenu.drawer,
    bottomNavigationBar: navMenu.bottomBar,
    ...