∀ {J : Type u_2} [inst : CategoryTheory.Category.{u_4, u_2} J] {C : Type u_3}
  [inst_1 : CategoryTheory.Category.{u_1, u_3} C] (F : CategoryTheory.Functor J C)
  {X Y : CategoryTheory.CostructuredArrow (CategoryTheory.Functor.const J) F} (f : X ⟶ Y),
  CategoryTheory.CategoryStruct.comp
      (((CategoryTheory.Limits.Cone.fromCostructuredArrow F).comp
            (CategoryTheory.Limits.Cone.toCostructuredArrow F)).map
        f)
      ((fun x => x.eta.symm) Y).hom =
    CategoryTheory.CategoryStruct.comp ((fun x => x.eta.symm) X).hom
      ((CategoryTheory.Functor.id (CategoryTheory.CostructuredArrow (CategoryTheory.Functor.const J) F)).map f)