∀ {α : Type u_1} {E : Type u_4} {m : MeasurableSpace α} {p : ENNReal} {μ : MeasureTheory.Measure α}
  [inst : NormedAddCommGroup E] {β : Type u_7} [inst_1 : MeasurableSpace β] {μb : MeasureTheory.Measure β} {f : α → β}
  [inst_2 : Fact (1 ≤ p)] (hf : MeasureTheory.MeasurePreserving f μ μb),
  Isometry ⇑(MeasureTheory.Lp.compMeasurePreserving f hf)