∀ {C₁ : Type u_8} {C₂ : Type u_6} {C₃ : Type u_2} {C₄ : Type u_4} [inst : CategoryTheory.Category.{u_7, u_8} C₁]
  [inst_1 : CategoryTheory.Category.{u_5, u_6} C₂] [inst_2 : CategoryTheory.Category.{u_1, u_2} C₃]
  [inst_3 : CategoryTheory.Category.{u_3, u_4} C₄] {T : CategoryTheory.Functor C₁ C₂} {L : CategoryTheory.Functor C₁ C₃}
  {R : CategoryTheory.Functor C₂ C₄} {B : CategoryTheory.Functor C₃ C₄} (w : CategoryTheory.TwoSquare T L R B) {X₂ : C₂}
  {X₃ : C₃} (g : R.obj X₂ ⟶ B.obj X₃) {f₁ f₂ : w.StructuredArrowRightwards g} (φ : f₁ ⟶ f₂),
  CategoryTheory.CategoryStruct.comp
      ((w.structuredArrowDownwards X₂).map (CategoryTheory.StructuredArrow.homMk φ.right.left ⋯))
      (CategoryTheory.CostructuredArrow.mk (CategoryTheory.StructuredArrow.homMk f₂.right.hom ⋯)).hom =
    (CategoryTheory.CostructuredArrow.mk (CategoryTheory.StructuredArrow.homMk f₁.right.hom ⋯)).hom