public function enableLanguage($ISO639_1, $name, $default_country_code, $default_lang = false)
    {
        $nb_language = new CNabuBuiltInLanguage();
        $nb_language->setISO6391($ISO639_1)
                    ->setName($name)
                    ->setDefaultCountryCode($default_country_code)
                    ->setEnabled(CNabuLanguage::LANGUAGE_ENABLED)
        ;

        $nb_site = $this->nb_engine->getHTTPServer()->getSite();
        $nb_site->setLanguage($nb_language);
        if ($default_lang) {
            $nb_site->setDefaultLanguage($nb_language);
        }

        return $nb_language;
    }