fact: Definition α_functors_inv (X : functor C D)(Y : functor D E)(Z : functor E F) : nat_trans (functor_composite X (functor_composite Y Z)) (functor_composite (functor_composite X Y) Z) := nat_trans_id ((X ∙ Y) ∙ Z).
imports: UniMath.Foundations.PartD UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory