public function xml()
    {
        $errorMessage = null;
        $internalErrors = libxml_use_internal_errors(true);
        $disableEntities = libxml_disable_entity_loader(true);
        libxml_clear_errors();

        try {
            $xml = new \SimpleXMLElement((string) $this->body ?: '<root />', LIBXML_NONET);
            if ($error = libxml_get_last_error()) {
                $errorMessage = $error->message;
            }
        } catch (\Exception $e) {
            $errorMessage = $e->getMessage();
        }

        libxml_clear_errors();
        libxml_use_internal_errors($internalErrors);
        libxml_disable_entity_loader($disableEntities);

        if ($errorMessage) {
            throw new RuntimeException('Unable to parse response body into XML: ' . $errorMessage);
        }

        return $xml;
    }