∀ {Ω : Type u_1} {𝓧 : Type u_2} {mΩ : MeasurableSpace Ω} {m𝓧 : MeasurableSpace 𝓧} {X Y : Ω → 𝓧}
  {μ : MeasureTheory.Measure 𝓧} {P : MeasureTheory.Measure Ω},
  ProbabilityTheory.HasLaw X μ P → Y =ᵐ[P] X → ProbabilityTheory.HasLaw Y μ P