proposition: Lemma isotoid_comp (C : category) (H : is_univalent C) (a b c : ob C) (e : z_iso a b) (f : z_iso b c) : isotoid _ H (z_iso_comp e f) = isotoid _ H e @ isotoid _ H f.
proof: Proof. apply idtoiso_inj. assumption. rewrite idtoiso_concat. repeat rewrite idtoiso_isotoid. apply idpath. Qed.
imports: UniMath.Foundations.PartA UniMath.Foundations.Sets UniMath.MoreFoundations.PartA UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos