∀ {Ω : Type u_1} {ι : Type u_2} {π : ι → Set (Set Ω)} {x : MeasurableSpace Ω} {μ : MeasureTheory.Measure Ω},
  ProbabilityTheory.iIndepSets π μ →
    ∀ (s : Finset ι) {f : ι → Set Ω}, (∀ i ∈ s, f i ∈ π i) → μ (⋂ i ∈ s, f i) = ∏ i ∈ s, μ (f i)