∀ {α : Type u_1} {m : MeasurableSpace α} {μ : MeasureTheory.Measure α} {E : Type u_8} [inst : NormedAddCommGroup E]
  [inst_1 : NormedSpace ℝ E] {f : α → NNReal},
  AEMeasurable f μ →
    ∀ {g : α → E},
      MeasureTheory.Integrable g (μ.withDensity fun x => ↑(f x)) ↔ MeasureTheory.Integrable (fun x => ↑(f x) • g x) μ