proposition: Lemma derivn_map p n : p^f^`(n) = (p^`(n))^f.
proof: Proof. by apply/polyP => i; rewrite !(coef_map, coef_derivn) //= rmorphMn. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)