proposition: Lemma cancel_z_iso' {M : precategory} {w x y : M} (g : z_iso w x) (f f' : x --> y) : g · f = g · f' -> f = f'.
proof: Proof. intro e. destruct g as [g [g' H]]. apply (pre_comp_with_z_iso_is_inj H). assumption. Qed.
imports: UniMath.Foundations.PartA UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories