Lemma is_iso_lunitor {a b : C} (f : hom_precategory a b) : is_iso (lunitor f : (hom_precategory a b) ⟦ identity a · f, f ⟧). Proof. apply is_iso_from_is_z_iso. apply is_z_iso_lunitor. Defined.
Require Import UniMath.Foundations.All. Require Import UniMath.MoreFoundations.All. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Isos. Require Import UniMath.CategoryTheory.Core.Functors. Require Import UniMath.CategoryTheory.Core.NaturalTransformations. Require Import UniMath.CategoryTheory.PrecategoryBinProduct.