proposition: Lemma polyseqX : 'X = [:: 0; 1] :> seq R.
proof: Proof. by rewrite unlock !polyseq_cons nil_poly eqxx /= polyseq1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)