∀ {α : Type u_1} {m : MeasurableSpace α} (μ : MeasureTheory.Measure α) [inst : MeasureTheory.IsFiniteMeasure μ]
  (s : Set α),
  MeasurableSet s → MeasureTheory.VectorMeasure.restrict μ.toSignedMeasure s = (μ.restrict s).toSignedMeasure