{T : Type u₁} →
  [inst : CategoryTheory.Category.{v₁, u₁} T] →
    {D : Type u₂} →
      [inst_1 : CategoryTheory.Category.{v₂, u₂} D] →
        {X : T} →
          (F : CategoryTheory.Functor T D) →
            CategoryTheory.Functor (CategoryTheory.Under X) (CategoryTheory.Under (F.obj X))