proposition: Lemma in_part_non0 sh i : is_part sh -> i \in sh -> i != 0.
proof: Proof. by move/notin0_part => + Hi; apply/contra => /eqP <-. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype