public function add(string $id): self
    {
        $app = App::get();
        if (\BearFramework\Addons::exists($id)) {
            $app->addons->add($id);
            if (isset(Internal\Data\Addons::$registrations[$id])) {
                $addon = new \BearCMS\Addons\Addon($id);
                call_user_func(Internal\Data\Addons::$registrations[$id], $addon);
                if (is_callable($addon->initialize)) {
                    call_user_func($addon->initialize);
                }
            }
        }
        return $this;
    }