proposition: Lemma lwhisker_lwhisker_rassociator_CAT {A B C D : category} {F : [A, B]} {G : [B, C]} {H I : [C, D]} (α : [C, D]⟦H, I⟧) : rassociator_CAT _ _ _ · lwhisker_CAT F (lwhisker_CAT G α) = lwhisker_CAT (functor_compose F G) α · rassociator_CAT _ _ _ .
proof: Proof. apply (nat_trans_eq D); intro c. cbn. rewrite id_right; apply id_left. Qed.
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