proposition: Lemma zmod_closedN : zmod_closed -> oppr_closed.
proof: Proof. by case=> S0 SB y Sy; rewrite -sub0r !SB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)