∀ {C : Type u_1} {D : Type u_2} [inst : CategoryTheory.Category.{v_1, u_1} C]
  [inst_1 : CategoryTheory.Category.{v_2, u_2} D] [inst_2 : CategoryTheory.Preadditive C]
  [inst_3 : CategoryTheory.Preadditive D] {F : CategoryTheory.Functor C D} [F.Additive] {G : CategoryTheory.Functor C D}
  (e : F ≅ G), G.Additive