∀ {C : Type u_3} [inst : CategoryTheory.Category.{u_4, u_3} C] {E : Type u_2}
  [inst_1 : CategoryTheory.Category.{u_1, u_2} E] {D : Type u_3} [inst_2 : CategoryTheory.Category.{u_4, u_3} D]
  (S : CategoryTheory.Functor C D) (T : CategoryTheory.Functor D E) ⦃X Y : E⦄ (f : X ⟶ Y),
  CategoryTheory.CategoryStruct.comp ((CategoryTheory.CostructuredArrow.functor (S.comp T)).map f)
      (CategoryTheory.CostructuredArrow.pre S T Y).toCatHom =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.CostructuredArrow.pre S T X).toCatHom
      ((CategoryTheory.CostructuredArrow.functor T).map f)