fact: Definition is_nat_id {C D : precategory} {F : C ⟶ D} (μ : F ⟹ F) : UU := ∏ (c : C), μ c = identity (F c).
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