Definition singleofintu (x: aval) :=
  match x with
  | I i => FS(Float32.of_intu i)
  | _   => ntop1 x
  end.

(* Specifications: *)
Lemma singleofintu_sound: forall v x w, vmatch v x -> Val.singleofintu v = Some w -> vmatch w (singleofintu x).