proposition: Fact scale_polyDl p : {morph scale_poly^~ p : a b / a + b}.
proof: Proof. by move=> a b /=; rewrite !scale_polyE raddfD mulrDl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)