proposition: Fact ffun_scaleA k1 k2 f : ffun_scale k1 (ffun_scale k2 f) = ffun_scale (k1 * k2) f.
proof: Proof. by apply/ffunP=> a; rewrite !ffunE scalerA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)