fact: Definition ocons {A B} (a:A) (o:option B) (l:list (A*B)) := match o with | None => l | Some b => (a,b)::l end.
imports: Coq(Bool BinPos Pnat Setoid SetoidList PeanoNat) Coq(Orders OrdersFacts OrdersLists) MMaps(Utils Interface OrdList GenTree)