{C : Type u} →
  [inst : CategoryTheory.Category.{v, u} C] →
    {F : CategoryTheory.Functor C CategoryTheory.Cat} →
      {X Y : CategoryTheory.Grothendieck F} → (self : X.Hom Y) → (F.map self.base).toFunctor.obj X.fiber ⟶ Y.fiber