proposition: Lemma toNat_shlBaux n : forall (p: BITS n), toNat (shlBaux p) = (toNat p).*2.
proof: Proof. move => p. by rewrite /shlBaux toNatCons. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype tuple zmodp div) ssrextra.tuple ssrextra.nat spec spec.properties operations mathcomp(ssralg)