∀ {α : Type u_1} {β : Type u_2} {E : Type u_3} [inst : MeasurableSpace α] [inst_1 : MeasurableSpace β]
  {μ : MeasureTheory.Measure α} {ν : MeasureTheory.Measure β} [inst_2 : NormedAddCommGroup E] [MeasureTheory.SFinite ν]
  [inst_4 : NormedSpace ℝ E] [MeasureTheory.SFinite μ] (s : Set α) (t : Set β) (f : α × β → E),
  ∫ (z : β × α) in t ×ˢ s, f z.swap ∂ν.prod μ = ∫ (z : α × β) in s ×ˢ t, f z ∂μ.prod ν