∀ {α : Type u_1} {β : Type u_2} {Ω : Type u_3} {mα : MeasurableSpace α} {mβ : MeasurableSpace β}
  {mΩ : MeasurableSpace Ω} [inst : Countable α] (κCond : α → ProbabilityTheory.Kernel β Ω)
  (h_atom : ∀ (x y : α), x ∈ measurableAtom y → κCond x = κCond y) (p : α × β),
  (ProbabilityTheory.Kernel.condKernelCountable κCond h_atom) p = (κCond p.1) p.2