code: function (discount, cb) {
  
  		Discount.destroy(discount.id)
  	    .exec(function (err, destroyedDiscounts){
  	      if (err) return cb(err);
  	      if (!destroyedDiscounts) return cb(null, null);
  	      Discount.afterStripeCustomerDiscountDeleted(destroyedDiscounts[0], function(err, discount){
  	      	cb(err, discount);
  	      });
  	    });
  	}
docs: Stripe Webhook customer.discount.deleted