proposition: Lemma pre_whisker_identity (A B : precategory_data) (C : category) (H : functor_data A B) (G : functor_data B C) : pre_whisker H (nat_trans_id G) = nat_trans_id (functor_composite_data H G).
proof: Proof. apply nat_trans_eq. - apply homset_property. - intro a. apply idpath. Qed.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.FunctorCategory