proposition: Lemma addBA n : associative (@addB n).
proof: Proof. move => x y z. destruct n; first apply trivialBits. apply toZp_inj. autorewrite with ZpHom. by rewrite addrA. 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)