public static function transform($xslFileName, DOMDocument $xml)
    {
        $xsl = new DOMDocument;
        $xsl->load(__DIR__.'/../../xslt/'.$xslFileName.'.xsl');

        $proc = new XSLTProcessor;
        $proc->importStyleSheet($xsl);

        libxml_use_internal_errors(true);

        $result = $proc->transformToXML($xml);

        foreach (libxml_get_errors() as $error) {
            //throw new \Exception($error->message);
        }

        return $result;
    }