fact: Fixpoint xfold (m : t A) (v : B) (i : key) := match m with | Leaf => v | Node l (Some x) r => xfold r (f (rev i) x (xfold l v i~0)) i~1 | Node l None r => xfold r (xfold l v i~0) i~1 end.
imports: Coq(Bool PeanoNat BinPos Orders OrdersEx OrdersLists) MMaps(Utils Comparisons Interface)