Very minor point, but where possible, could you please make it so that all the error cases are handled above and the happy path is the last thing on the bottom? So:

```python
if not groups:
    return Response({}, status=status.HTTP_404_NOT_FOUND)

response_data = {
    'course_id': course_id,
    'module_id': module_id,
    'group_id': group_id,
}
return Response(response_data, status=status.HTTP_200_OK)
```