public function add($title, $description, $pageUrl, $iconUrl, $comment = '')
    {
        $params = [
            'title' => $title,
            'description' => $description,
            'page_url' => $pageUrl,
            'icon_url' => $iconUrl,
        ];
        if ($comment !== '') {
            $params['comment'] = $comment;
        }

        return $this->parseJSON('json', [self::API_ADD, $params]);
    }