proposition: Lemma triangle_l {X Y Z : C} (g : C⟦Y,Z⟧) (f : C⟦X,Y⟧) : lunitor g ⋆⋆ id₂ f o rassociator _ _ _ = id₂ g ⋆⋆ runitor f.
proof: Proof. rewrite triangle_r. rewrite vassocr. rewrite <- inverse_of_assoc. rewrite vcomp_linv. rewrite id2_left. apply idpath. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Invertible_2cells UniMath.Bicategories.Core.Unitors