∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {E : Type u₃} [inst_1 : CategoryTheory.Category.{v₃, u₃} E]
  {D : Type u₁} [inst_2 : CategoryTheory.Category.{v₁, u₁} D] (S : CategoryTheory.Functor C D)
  (T : CategoryTheory.Functor D E) (e : E),
  (CategoryTheory.CostructuredArrow.preFunctor S T).app e = (CategoryTheory.CostructuredArrow.pre S T e).toCatHom