fact: Definition is_nat_trans {C C' : precategory_data} (F F' : functor_data C C') (t : nat_trans_data F F') := ∏ (x x' : ob C)(f : x --> x'), # F f · t x' = t x · #F' f.
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