public static function create_cartridge($toolid) {
        $cartridge = new \DOMDocument();
        $cartridge->load(realpath(__DIR__ . '/../xml/imslticc.xml'));
        $xpath = new \DOMXpath($cartridge);
        $xpath->registerNamespace('cc', 'http://www.imsglobal.org/xsd/imslticc_v1p0');
        $parameters = self::get_cartridge_parameters($toolid);
        self::set_xpath($xpath, $parameters);

        return $cartridge->saveXML();
    }