fact: Definition fold_impl (m:monoid_op B) (f:A->nat->B) (E:multiset A) := LibList.fold_right (fun p acc => let (x,n) := p : A*nat in monoid_oper m (f x n) acc) (monoid_neutral m) (to_list_impl E).
imports: TLC(LibTactics LibLogic LibReflect LibRelation LibList LibInt LibNat LibOperation LibEpsilon LibSet LibMonoid)