proposition: Lemma toNat_zeroExtend extra n (p: BITS n) : toNat (zeroExtend extra p) = toNat p.
proof: Proof. rewrite /zeroExtend. rewrite toNatCat. by rewrite toNat_zero. Qed.
imports: Coq(ZArith.ZArith) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype tuple div zmodp ssralg) ssrextra.nat ssrextra.tuple spec.spec