proposition: Lemma lead_coefC c : lead_coef c%:P = c.
proof: Proof. by rewrite /lead_coef polyseqC; case: eqP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)