∀ {C₁ : Type u_1} {C₂ : Type u_2} [inst : CategoryTheory.Category.{v_1, u_1} C₁]
  [inst_1 : CategoryTheory.Category.{v_2, u_2} C₂] {W₁ : CategoryTheory.MorphismProperty C₁}
  {W₂ : CategoryTheory.MorphismProperty C₂} {Φ : CategoryTheory.LocalizerMorphism W₁ W₂} {X₂ : C₂}
  (L : Φ.LeftResolution X₂),
  (CategoryTheory.LocalizerMorphism.LeftResolution.Hom.id L).f = CategoryTheory.CategoryStruct.id L.X₁