| MQSortedBy of mqlist * mqorder * mqfunc (* ordering *)
| MQDiff of mqlist * mqlist (* set difference *)
| MQLetIn of mqlvar * mqlist * mqlist (* explicit lvar assignment *)
| MQSortedBy of mqlist * mqorder * mqfunc (* ordering *)
| MQDiff of mqlist * mqlist (* set difference *)
| MQLetIn of mqlvar * mqlist * mqlist (* explicit lvar assignment *)