proposition: Lemma nat_z_iso_id {C D:category} (F: C ⟶ D): nat_z_iso F F.
proof: Proof. apply (make_nat_z_iso F F (nat_trans_id F)). intro c. exists (identity (F c)). split; apply id_left. Defined.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.TransportMorphisms UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Univalence