Nestable\Services\NestableService::ul PHP Метод

    public function ul($items = false, $parent_id = 0)
    {
        $attrs = '';
        if (is_array($this->optionUlAttr) && count($this->optionUlAttr) > 0) {
            $attrs = $this->renderAttr($this->optionUlAttr, $parent_id);
        }
        if (!$items) {
            return "\n" . '<ul' . $attrs . '>' . "\n";
        }
        return '<ul' . $attrs . '>' . "\n" . $items . "\n" . '</ul>';
    }