public function ofType($type)
    {
        $items = [];

        foreach ($this->items as $path => $slug) {
            $page = $this->pages->get($path);
            if ($page !== null && $page->template() === $type) {
                $items[$path] = $slug;
            }
        }

        $this->items = $items;

        return $this;
    }