∀ (M : Type u_1) {α : Type u_2} [inst : TopologicalSpace α] [inst_1 : Monoid M] [inst_2 : MulAction M α]
  [h : MulAction.IsTopologicallyTransitive M α] {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m, m • U)