Definition super_non_expansive' {A} P := forall n ts x, compcert_rmaps.RML.R.approx n (P ts x) =
compcert_rmaps.RML.R.approx n (P ts (functors.MixVariantFunctor.fmap (rmaps.dependent_type_functor_rec ts A)
(compcert_rmaps.RML.R.approx n) (compcert_rmaps.RML.R.approx n) x)).

(* tactics *)
Lemma void_ret : ifvoid tvoid (` (PROP ( )  LOCAL ()  SEP ()) (make_args [] []))
(EX v : val, ` (PROP ( )  LOCAL ()  SEP ()) (make_args [ret_temp] [v])) = emp.