∀ {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) (ca : α × γ),
  (ProbabilityTheory.Kernel.prodMkRight γ κ) ca = κ ca.1