proposition: Lemma coef_map p i : p^f`_i = f p`_i.
proof: Proof. exact: coef_map_id0 (raddf0 f). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)