public function preRender(Event $event)
    {
        $markdown = $event->getParam('markdown');

        $markdownHash = md5($markdown);

        $success = false;
        $renderedMarkdown = $this->cache->getItem($markdownHash, $success);
        if ($success) {
            $event->stopPropagation(true);

            return $renderedMarkdown;
        }

        return false;
    }