proposition: Lemma idtoiso_precompose (C : precategory) (a a' b : ob C) (p : a = a') (f : a --> b) : (idtoiso (!p)) · f = transportf (λ a, a --> b) p f.
proof: Proof. destruct p. apply id_left. Qed.
imports: UniMath.Foundations.PartA UniMath.Foundations.Sets UniMath.MoreFoundations.PartA UniMath.MoreFoundations.Tactics UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos