protected function createSubscriptionOnStripe(Request $request, $user)
    {
        $plan = Spark::plans()->find($request->plan);

        $subscription = $user->subscription($plan->id);

        if ($plan->hasTrial()) {
            $subscription->trialFor(Carbon::now()->addDays($plan->trialDays));
        }

        if ($request->coupon) {
            $subscription->withCoupon($request->coupon);
        }

        $subscription->create($request->stripe_token, [
            'email' => $user->email,
        ]);
    }