proposition: Fact ffun_scale_addr k : {morph (ffun_scale k) : x y / x + y}.
proof: Proof. by move=> f g; apply/ffunP=> a; rewrite !ffunE scalerDr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)