proposition: Lemma runitor_triangle {a b c: C} (f : C⟦a, b⟧) (g : C⟦b, c⟧) : rassociator f g (identity c) • (f ◃ runitor g) = runitor (f · g).
proof: Proof. apply rwhisker_id_inj. etrans. 2: apply runitor_rwhisker_rwhisker. apply pathsinv0, rwhisker_vcomp. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Invertible_2cells UniMath.Bicategories.Core.Examples.OpMorBicat UniMath.Bicategories.Core.Examples.OpCellBicat