(** * Fold *)
Notation NoDup := (NoDupA E.eq).
Notation InA := (InA E.eq).
(** Alternative specification via [fold_right] *)

(* Specifications: *)
Lemma fold_spec_right (s:t)(A:Type)(i:A)(f : elt -> A -> A) :
fold f s i = List.fold_right f i (rev (elements s)).