proposition: Lemma class_lcoset x y A : x ^: (y *: A) = (x ^ y) ^: A.
proof: Proof. by rewrite classM class_set1 class_support_set1l. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)