proposition: Lemma is_iso_from_is_z_iso {C : precategory} {a b : C} (f: a --> b) : is_z_isomorphism f -> is_iso f.
proof: Proof. intro H. apply (is_iso_qinv _ (pr1 H)). apply (pr2 H). Defined.
imports: UniMath.Foundations.PartA UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories