mp_encode_array(tuple_buf, 0); /* clear */
tuple_pointer = mp_encode_array(tuple_pointer, 1);
if(n == 0) tuple_pointer = mp_encode_str(tuple_pointer, "INSERTED", 8);
else tuple_pointer = mp_encode_str(tuple_pointer, "NOTINSERTED", 11);
return box_return_mp(ctx, tuple, tuple_pointer);