{
  "summary": "Update a subscriber",
  "method": "PUT",
  "path": "/v4/subscribers/{id}",
  "tag": "Subscribers",
  "request_body": {
    "first_name": "string",
    "email_address": "string",
    "fields": {}
  },
  "response": {
    "subscriber": {
      "id": 1,
      "first_name": "string",
      "email_address": "string",
      "state": "active",
      "created_at": "string"
    },
    "warnings": [
      "string"
    ]
  }
}