∀ {α : Type u_1} {β : Type u_2} {mα : MeasurableSpace α} {mβ : MeasurableSpace β} {f : β → ENNReal}
  {μ : MeasureTheory.Measure β} {a : α}, ∫⁻ (x : β), f x ∂(ProbabilityTheory.Kernel.const α μ) a = ∫⁻ (x : β), f x ∂μ