Lemma isaprop_is_iso {C : precategory_data} (a b : C) (f : a --> b) : isaprop (is_iso f). Proof. apply impred; intro. apply isapropisweq. Qed.
Require Import UniMath.Foundations.PartA. Require Import UniMath.Foundations.Propositions. Require Import UniMath.Foundations.Sets. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.CategoryTheory.Core.Categories.