Fixpoint extendr {A} (l : list A) ls :=
match l, ls with
| x :: xs, y :: ys => (y ++ [x]) :: extendr xs ys
| _, _ => ls
end.

(* This lets us use a library as a client. *)
Lemma semax_body_mono : forall V G {cs : compspecs} f s V2 G2
(HV : incl V V2) (HG : incl G G2) (Hdistinct : NoDup (map fst V2 ++ map fst G2)),
semax_body V G f s -> semax_body V2 G2 f s.