proposition: Lemma class_support_subG A : A \subset G -> class_support A G \subset G.
proof: Proof. by move=> sAG; rewrite class_supportEr; apply/bigcupsP=> x Gx; apply: conj_subG. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)