proposition: Lemma mulrbz x (b : bool) : x *~ b = (if b then x else 0).
proof: Proof. by case: b. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)