∀ {Ω : Type u_1} {m mΩ : MeasurableSpace Ω} {μ : MeasureTheory.Measure Ω},
  m ≤ mΩ →
    ∀ (f : MeasureTheory.SimpleFunc Ω ℝ) {g : Ω → ℝ}, MeasureTheory.Integrable g μ → μ[⇑f * g | m] =ᵐ[μ] ⇑f * μ[g | m]