proposition: Lemma getBit_shlB_0: forall n (bs: BITS n), getBit (shlB bs) 0 = false.
proof: Proof. elim=> [bs|n Hn /tupleP[b bs]]. by rewrite tuple0 /getBit. by rewrite /shlB /shlBaux getBit_dropmsb. 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)