Fixpoint Power_e (n:nat) : Cobham :=
match n with
| 0 => One_e 1
| S n' => Comp 1 Mult_e [Proj 1 0; Power_e n']
end.

Lemma Power_correct : forall n l,
length (Sem (Power_e n) l) = power (length (hd nil l)) n.