Definition lwhisker_CAT {C D E : category} (F : [C, D]) {G1 G2 : [D, E]} : [D, E]⟦G1, G2⟧ -> [C, E]⟦functor_compose F G1, functor_compose F G2⟧. Proof. intro α. exact (pre_whisker (F : functor _ _) α). 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.