fact: Definition nat_trans_comp_id_left (F G : functor A B) (α: nat_trans F G): nat_trans_comp _ _ _ (nat_trans_id F) α = α.
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