proposition: Lemma subset_neq0 A B : A \subset B -> A != set0 -> B != set0.
proof: Proof. by rewrite -!proper0 => sAB /proper_sub_trans->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop)