∀ {α : Type u_1} {mα : MeasurableSpace α} (μ ν : MeasureTheory.Measure α) [MeasureTheory.SigmaFinite μ],
  (fun x => Real.exp (MeasureTheory.llr μ ν x)) =ᵐ[ν] fun x => if μ.rnDeriv ν x = 0 then 1 else (μ.rnDeriv ν x).toReal