(** [removelast l] remove the last element of [l] *)

(* Specifications: *)
Lemma app_removelast_last :
forall l d, l <> [] -> l = removelast l ++ [last l d].
Lemma exists_last :
forall l, l <> [] -> { l' : (list A) & { a : A | l = l' ++ [a]}}.
Lemma removelast_app :
forall l l', l' <> [] -> removelast (l++l') = l ++ removelast l'.
Lemma removelast_last : forall l a, removelast (l ++ [a]) = l.
Hypothesis eq_dec : forall x y : A, {x = y}+{x <> y}.