protected function validateCoupon($validator, Request $request)
    {
        try {
            $coupon = StripeCoupon::retrieve(
                $request->coupon, ['api_key' => config('services.stripe.secret')]
            );

            if ($coupon && $coupon->valid) {
                return;
            }
        } catch (Exception $e) {
            //
        }

        $validator->errors()->add('coupon', 'The provided coupon code is invalid.');
    }