fact: Definition is_iso_qinv {C:precategory} {a b : C} (f : a --> b) (g : b --> a) : is_inverse_in_precat f g -> is_iso f.
imports: UniMath.Foundations.PartA UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories