curl --request POST \
  --url https://api-dev.withflock.com/customers/identify \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "externalUserId": "customer_123",
  "email": "<string>",
  "name": "<string>",
  "customProperties": {}
}'

{
  "id": "<string>",
  "externalUserId": "<string>",
  "email": "<string>",
  "name": "<string>",
  "referredBy": {
    "id": "<string>",
    "externalUserId": "<string>",
    "email": "<string>",
    "name": "<string>"
  },
  "referredById": {},
  "referredByReferralId": "<string>",
  "referredInCampaignId": "<string>",
  "visitedReferralsCount": 123,
  "convertedReferralsCount": 123,
  "referralCode": "<string>",
  "createdAt": "2023-11-07T05:31:56Z",
  "updatedAt": "2023-11-07T05:31:56Z",
  "deletedAt": "2023-11-07T05:31:56Z",
  "organizationId": "<string>",
  "applicationId": "<string>",
  "customProperties": {}
}