curl --request GET \
  --url https://app.ezzydoc.com/EzzyService.svc/Rest/getInvoiceColumns

{
  "columns": [
    {
      "coltype": 123,
      "description": "<string>",
      "name": "<string>"
    }
  ],
  "service_status": {
    "invoice_id": 123,
    "message": "<string>",
    "status": 0
  }
}