def METHOD_NAME(self) -> Union[str, Tuple[str, Dict[str, int]]]:
    trace_ids = self._get_param("TraceIds")
    # next_token = self._get_param('NextToken')  # not implemented yet
    if trace_ids is None:
        msg = "Parameter TraceIds is missing"
        return (
            json.dumps({"__type": "MissingParameter", "message": msg}),
            dict(status=400),
        )
    result: Dict[str, Any] = {"Services": []}
    return json.dumps(result)