proposition: Lemma is_iso_lassociator {a b c d : C} (f : hom_precategory a b) (g : hom_precategory b c) (h : hom_precategory c d) : is_iso (lassociator f g h : (hom_precategory a d) ⟦ f · (g · h), (f · g) · h ⟧).
proof: Proof. apply is_iso_from_is_z_iso. apply is_z_iso_lassociator. Defined.
imports: UniMath.Tactics.EnsureStructuredProofs UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.PrecategoryBinProduct