(* Lemmas that DO NOT depend on CompCert or Verifiable C *)
Definition Vector_0_is_nil (T : Type) (v : Vector.t T 0) : v = Vector.nil T :=
match v with Vector.nil => eq_refl end.
intros. inversion H; split; trivial. Qed.
*)

Lemma skipn_app2:
forall A n (al bl: list A),
(n >= length al)%nat ->
skipn n (al++bl) = skipn (n-length al) bl.