∀ {α : Type u_4} {β : Type u_5} {γ : Type u_6} {mα : MeasurableSpace α} {mβ : MeasurableSpace β}
  {mγ : MeasurableSpace γ} {μ ν : MeasureTheory.Measure (α × β × γ)} [MeasureTheory.IsFiniteMeasure μ],
  (∀ {s : Set α} {t : Set β} {u : Set γ},
      MeasurableSet s → MeasurableSet t → MeasurableSet u → μ (s ×ˢ t ×ˢ u) = ν (s ×ˢ t ×ˢ u)) →
    μ = ν