Opaque MultTwoPowerLength_e.
(** Def 14 of (Rose) *)
Definition DivTwoPower'_e : Cobham :=
Rec2
(Proj 1 0)
(Comp 3 Div2_e [Proj 3 1])
(Proj 2 1).

Lemma length_DivTwoPower' : forall l,
length (Sem DivTwoPower'_e l) = length (hd nil (tl l)) - length (hd nil l).