∀ {ι : Type u_1} {α : Type u_2} {β : Type u_3} {m0 : MeasurableSpace α} [inst : MeasurableSpace β] {f : α → β}
  [Countable ι] {μ : ι → MeasureTheory.Measure α},
  (∀ (i : ι), AEMeasurable f (μ i)) → AEMeasurable f (MeasureTheory.Measure.sum μ)