proposition: Lemma fin_numM x y : x \is a fin_num -> y \is a fin_num -> x * y \is a fin_num.
proof: Proof. by move: x y => [x| |] [y| |]. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed