Definition post_whisker {B C D : precategory_data} {G H : functor_data B C} (gamma : nat_trans G H) (K : functor C D) : nat_trans (functor_composite_data G K) (functor_composite_data H K). Proof. exists (λ a : ob B, #(pr1 K) (pr1 gamma a)). apply is_nat_trans_post_whisker. Defined.
Require Import UniMath.Foundations.PartD. Require Import UniMath.Foundations.Propositions. Require Import UniMath.Foundations.Sets. 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.