public function parentTag(): ?string
    {
        switch ($this->attributes['list']) {
            case Options::ATTRIBUTE_LIST_ORDERED:
                return Options::HTML_TAG_LIST_ORDERED;
                break;
            case Options::ATTRIBUTE_LIST_BULLET:
                return Options::HTML_TAG_LIST_UNORDERED;
                break;

            default:
                return Options::HTML_TAG_LIST_UNORDERED;
                break;
        }
    }