curl --request POST \
  --url https://api.flatpeak.com/customers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "reference_id": "CUS1234567890"
}'

{
  "id": "cus_65e421d1daa4a24082b4f590",
  "object": "customer",
  "live_mode": true,
  "reference_id": "CUS1234567890",
  "locations": [
    "loc_641b90b758fb8e6293716e40"
  ],
  "time_created": "2021-05-05T05:37:27Z",
  "account_id": "acc_65e421bed29d88d9012e0662"
}