proposition: Lemma fold_cons : forall m f x l, fold m f (x::l) = monoid_oper m (f x) (fold m f l).
proof: Proof. Proof using. auto. Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)