Definition opt_beq (ox oy: option L.t) : bool :=
  match ox, oy with
  | None, None => true
  | Some x, Some y => L.beq x y
  | _, _ => false
  end.

(* Specifications: *)
Lemma opt_beq_correct: forall ox oy, opt_beq ox oy = true -> opt_eq ox oy.