Opaque Div2_e.
(** Def 5 of (Rose) *)
Definition Mod2_e : Cobham :=
Rec
Zero
(False_e 2)
(One_e 2)
(One_e 1).

Lemma Mod2_correct_bs : forall l,
(hd nil l) <> nil ->
Sem Mod2_e l = [hd true (hd nil l)].