Opaque DivTwoPower'_e.
Definition DivTwoPower_e : Cobham :=
Comp 2 DivTwoPower'_e [Proj 2 1; Proj 2 0].

Lemma DivTwoPower_correct_bs : forall l,
Sem DivTwoPower_e l =
fun_power (length (hd nil (tl l))) (@tl _) (hd nil l).