proposition: Lemma cancel_postcomposition_iso {C : precategory} {a b c : C} (h : iso b c) (f g : a --> b) : f · h = g · h -> f = g.
proof: Proof. apply (post_comp_with_iso_is_inj _ _ (pr1 h) (pr2 h)). Qed.
imports: UniMath.Foundations.PartA UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories