proposition: Lemma size_polyC c : size c%:P = (c != 0).
proof: Proof. by rewrite polyseqC size_nseq. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)