∀ {B : Type u_1} [inst : CategoryTheory.Bicategory B] {a b c d : Bᵒᵖ} (f : a ⟶ b) (g : b ⟶ c) {h h' : c ⟶ d}
  (η : h ⟶ h'),
  Bicategory.Opposite.op2
      (CategoryTheory.Bicategory.whiskerRight η.unop2 (CategoryTheory.CategoryStruct.comp f g).unop) =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.Bicategory.associator h.unop g.unop f.unop).op2_unop.symm.hom
      (CategoryTheory.CategoryStruct.comp
        (Bicategory.Opposite.op2
          (CategoryTheory.Bicategory.whiskerRight
            (Bicategory.Opposite.op2 (CategoryTheory.Bicategory.whiskerRight η.unop2 g.unop)).unop2 f.unop))
        (CategoryTheory.Bicategory.associator h'.unop g.unop f.unop).op2_unop.symm.inv)