public function getReference($response, $isRedirect)
    {
        if ($isRedirect) {
            return Arr::get($response, 'TOKEN', '');
        }

        foreach (['REFUNDTRANSACTIONID',
            'TRANSACTIONID',
            'PAYMENTINFO_0_TRANSACTIONID',
            'AUTHORIZATIONID', ] as $key) {
            if (isset($response[$key])) {
                return $response[$key];
            }
        }
    }