private function filename($url, $title = '')
    {
        if (!empty($title)) {
            $filename = $this->slug($title);
        } else {
            $filename = $this->slug(pathinfo($url, PATHINFO_FILENAME));
        }

        $extention = pathinfo($url, PATHINFO_EXTENSION);
        if (!empty($extention)) {
            return $filename.'.'.$extention;
        }

        return $filename;
    }