∀ {E : Type u_2} {X : Type u_1} [inst : TopologicalSpace E] [inst_1 : TopologicalSpace X] {f : E → X} {G : Type u_3}
  [inst_2 : Group G] [inst_3 : MulAction G E],
  Topology.IsQuotientMap f →
    ∀ [ContinuousConstSMul G E] (U : Set E), IsOpen U → f ⁻¹' (f '' U) = ⋃ g, (fun x => g • x) ⁻¹' U → IsOpen (f '' U)