∀ {α : Type u_1} [inst : MeasurableSpace α] {M : Type u_4} [inst_1 : TopologicalSpace M] [inst_2 : AddCommMonoid M]
  [T2Space M] [inst_4 : ContinuousAdd M] (v : MeasureTheory.VectorMeasure α M) {i : Set α},
  MeasurableSet i → v.restrict i + v.restrict iᶜ = v