∀ {α : Type u_1} {β : Type u_2} {γ : Type u_3} {mα : MeasurableSpace α} {mβ : MeasurableSpace β}
  {mγ : MeasurableSpace γ} (κ : ProbabilityTheory.Kernel α (β × γ)) [ProbabilityTheory.IsMarkovKernel κ],
  ProbabilityTheory.IsMarkovKernel κ.snd