protected function extractParam(\SimpleXMLElement $element)
    {
        $param = array();
        foreach ($element as $subElement) {
            if (count($subElement) === 0) {
                $param[$subElement->getName()] = (string)$subElement;
            } else {
                $param[$subElement->getName()] = $this->extractParam($subElement);
            }
        }

        return $param;
    }