∀ {C : Type u_1} [inst : CategoryTheory.Category.{u_3, u_1} C] {D : Type u_4}
  [inst_1 : CategoryTheory.Category.{u_2, u_4} D] (T : CategoryTheory.Functor C D) (d : Dᵒᵖ),
  (CategoryTheory.StructuredArrow.map (CategoryTheory.CategoryStruct.id d).unop).toCatHom =
    CategoryTheory.CategoryStruct.id (CategoryTheory.Cat.of (CategoryTheory.StructuredArrow (Opposite.unop d) T))