(r2,fv2,st2) ->
(r2, fv1 `plusOccEnv` fv2, st2)
-getState :: TM TickTransState
-getState = TM $ \ env st -> (st, noFVs, st)
+-- getState :: TM TickTransState
+-- getState = TM $ \ env st -> (st, noFVs, st)
setState :: (TickTransState -> TickTransState) -> TM ()
setState f = TM $ \ env st -> ((), noFVs, f st)