proposition: Lemma horcomp_id_postwhisker (A B C : category) (X X' : [A, B]) (α : X --> X') (Z : [B, C]) : horcomp α (nat_trans_id _ ) = post_whisker α Z.
proof: Proof. apply nat_trans_eq_alt; intro a; apply id_left. Qed.
imports: UniMath.Foundations.PartD UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.whiskering UniMath.CategoryTheory.PrecategoryBinProduct UniMath.CategoryTheory.FunctorCategory UniMath.CategoryTheory.UnitorsAndAssociatorsForEndofunctors