discount

record discount {
  checkout-session: option​<string>,
  coupon: coupon,
  customer: option​<string>,
  end: option​<s32>,
  id: string,
  invoice: option​<string>,
  invoice-item: option​<string>,
  object: discount-object-enum,
  promotion-code: option​<string>,
  start: s32,
  subscription: option​<string>,
}