curl --request POST \
  --url https://api.withflex.com/v1/coupons \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "coupon": {
    "name": "Coupon",
    "applies_to": {
      "products": [
        "<string>"
      ]
    },
    "amount_off": 100,
    "duration": "<unknown>",
    "duration_in_months": null,
    "percent_off": 10,
    "max_redemptions": 100,
    "metadata": {
      "key": "value"
    }
  }
}
'

{
  "coupon": {
    "coupon_id": "fcoup_1234567890",
    "duration": "<unknown>",
    "name": "<string>",
    "valid": true,
    "created_at": "<string>",
    "test_mode": true,
    "amount_off": 123,
    "applies_to": {
      "products": [
        "<string>"
      ]
    },
    "duration_in_months": 123,
    "metadata": {},
    "percent_off": 123,
    "max_redemptions": 123,
    "times_redeemed": 123
  }
}