proposition: Lemma size_codesz c : size c = n.
proof: Proof. Proof using. by case: c => c /= /andP[_ /eqP]. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(fingroup perm morphism presentation) mathcomp(ssralg poly ssrint) permcomp tools permuted combclass congr