∀ {α : Type u_1} {β : Type u_2} [inst : MeasurableSpace α] [inst_1 : MeasurableSpace β] {μa : MeasureTheory.Measure α}
  {μb : MeasureTheory.Measure β} {f : α → β},
  MeasureTheory.MeasurePreserving f μa μb →
    ∀ {s : Set β}, MeasurableSet s → MeasureTheory.MeasurePreserving f (μa.restrict (f ⁻¹' s)) (μb.restrict s)