proposition: Lemma xorBNaux : forall n (b : BITS n), xorB b (invB b) = ones _.
proof: Proof. move => n b. by rewrite -xorBN xorBA xorBB xor0B. 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