HTTP response codes
    | Code | Description | 
|---|---|
| 200 | Succeeded | 
| 401 | The auth token is invalid, or for any reason the user can't pass the
         token verification. It is possible for the server to return a 200 code and an empty user
         list in the response body at the same time. This indicates that the service runs, but it
         can't find any user with the given search key. | 
| 500 | Internal server error.  |