fact: Example ex_mapAccumL_1 : mapAccumL (fun n x => (n+1, x+2)) 0 [1; 2; 3] = (3, [3; 4; 5]).
imports: Hask.Ltac Hask.Control.Monad Hask.Data.Eq Hask.Data.Maybe Coq.Program.Wf Coq.Sorting.Sorted Coq.Classes.RelationClasses Coq.Lists.List