∀ (J : Type u) [inst : CategoryTheory.Category.{v, u} J] {F G : CategoryTheory.Functor J (Type w)} (φ : F ⟶ G)
  (x : ↑F.sections) (j : J), ↑((CategoryTheory.Functor.sectionsFunctor J).map φ x) j = φ.app j (↑x j)