app\ControllerProvider::homepage PHP Method

    public function homepage(App $app)
    {
        $app['session']->getFlashBag()->add('warning', 'Warning flash message');
        $app['session']->getFlashBag()->add('info', 'Info flash message');
        $app['session']->getFlashBag()->add('success', 'Success flash message');
        $app['session']->getFlashBag()->add('danger', 'Danger flash message');
        return $app['twig']->render('index.html.twig');
    }