/**
  * Deteremine if the customer has a subscription.
  *
  * @param  \Stripe_Customer  $customer
  * @return bool
  */
 protected function usingMultipleSubscriptionApi($customer)
 {
     return !isset($customer->subscription) && count($customer->subscriptions) > 0 && !is_null($this->billable->getStripeSubscription());
 }