xbt_assert(data_object.HasMember("timestamp"),"Invalid JSON message: the 'data' value of event %d (CALL_ME_LATER) should contain a 'timestamp' key.",event_number);
xbt_assert(timestamp_value.IsDouble(),"Invalid JSON message: the 'timestamp' value in the 'data' value of event %d (CALL_ME_LATER) should be a double.",event_number);
xbt_assert(timestamp_value.IsNumber(),"Invalid JSON message: the 'timestamp' value in the 'data' value of event %d (CALL_ME_LATER) should be a number.",event_number);