proposition: Lemma is_functor_Fun3 : is_functor Fun3_functor_data.
proof: Proof. split; [ intro F | intros F G H α β ]; use (nat_trans_eq has_homsets_HSET); intro X; use funextsec; intro f; [ use id_right | use assoc ]. Qed.
imports: UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Limits.BinProducts UniMath.CategoryTheory.exponentials UniMath.CategoryTheory.whiskering UniMath.CategoryTheory.opp_precat UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.RightKanExtension UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.yoneda UniMath.CategoryTheory.YonedaBinproducts UniMath.CategoryTheory.Categories.HSET.Core UniMath.CategoryTheory.Categories.HSET.Limits UniMath.CategoryTheory.Categories.HSET.Structures UniMath.CategoryTheory.Categories.HSET.MonoEpiIso UniMath.CategoryTheory.Limits.Graphs.Limits UniMath.CategoryTheory.Presheaf