curl --request GET \
  --url https://app.flowglad.com/api/v1/discounts/{id} \
  --header 'Authorization: <api-key>'

{
  "discount": {
    "id": "<string>",
    "createdAt": 0,
    "updatedAt": 0,
    "livemode": true,
    "organizationId": "<string>",
    "name": "<string>",
    "code": "<string>",
    "amount": 123,
    "amountType": "percent",
    "active": true,
    "duration": "<string>",
    "redemptionCount": 123,
    "numberOfPayments": "<unknown>"
  }
}