Definition rwhisker_CAT {C D E : category} {F1 F2 : [C, D]} (G : [D, E]) : [C, D]⟦F1, F2⟧ -> [C, E]⟦functor_compose F1 G, functor_compose F2 G⟧. Proof. intro α. exact (post_whisker α (G : functor _ _)). Defined.
Require Import UniMath.Foundations.PartD. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Functors. Require Import UniMath.CategoryTheory.Core.Isos. Require Import UniMath.CategoryTheory.Core.NaturalTransformations. Require Import UniMath.CategoryTheory.FunctorCategory. Require Import UniMath.CategoryTheory.whiskering.