fact: Definition cons_poly c p : {poly R} := if p is Polynomial ((_ :: _) as s) ns then @Polynomial R (c :: s) ns else c%:P.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)