@type t() :: %Rapyd.Types.Coupon{
  amount_off: float() | nil,
  created_at: integer(),
  currency: String.t() | nil,
  duration: String.t(),
  duration_in_months: integer() | nil,
  id: String.t(),
  max_redemptions: integer() | nil,
  metadata: map() | nil,
  percent_off: float() | nil,
  redeem_by: integer() | nil,
  valid: boolean()
}