∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y Z : C} (α : X ≅ Y) {f : Z ⟶ X} {g : Z ⟶ Y},
  CategoryTheory.CategoryStruct.comp f α.hom = g ↔ f = CategoryTheory.CategoryStruct.comp g α.inv