public static function loadClassFromTagName($tagName, $throwException = true)
    {
        $tagName = str_ireplace('/rdf:rdf/rdf:description/', '', $tagName);

        if ('' === trim($tagName)) {
            return new NoSource();
        }

        try {
            return TagFactory::getFromTagname($tagName);
        } catch (TagUnknown $exception) {
            if ($throwException) {
                throw new NotFoundHttpException(sprintf("Tag %s not found", $tagName), $exception);
            }
        }

        return new NoSource($tagName);
    }