fact: Definition lassociator_CAT {C D E F : category} (X : [C, D]) (Y : [D, E]) (Z : [E, F]) : [C, F] ⟦functor_compose X (functor_compose Y Z), functor_compose (functor_compose X Y) Z⟧ := nat_trans_id (functor_composite X (functor_composite 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 UniMath.CategoryTheory.whiskering