∀ {C : Type u_10} [inst : CategoryTheory.Category.{u_9, u_10} C] {D : Type u_12}
  [inst_1 : CategoryTheory.Category.{u_11, u_12} D] {T : Type u_2} [inst_2 : CategoryTheory.Category.{u_1, u_2} T]
  {L : CategoryTheory.Functor C T} {R : CategoryTheory.Functor D T} {C' : Type u_6}
  [inst_3 : CategoryTheory.Category.{u_5, u_6} C'] {D' : Type u_8} [inst_4 : CategoryTheory.Category.{u_7, u_8} D']
  {T' : Type u_4} [inst_5 : CategoryTheory.Category.{u_3, u_4} T'] {L' : CategoryTheory.Functor C' T'}
  {R' : CategoryTheory.Functor D' T'} {F₁ : CategoryTheory.Functor C C'} {F₂ : CategoryTheory.Functor D D'}
  {F : CategoryTheory.Functor T T'} (α : F₁.comp L' ⟶ L.comp F) (β : R.comp F ⟶ F₂.comp R')
  [inst_6 : CategoryTheory.IsIso β] (X : CategoryTheory.Comma L' R')
  {Y Z : CategoryTheory.StructuredArrow X (CategoryTheory.Comma.map α β)} (f : Y ⟶ Z),
  CategoryTheory.CategoryStruct.comp
      ((CategoryTheory.StructuredArrow.map₂ (CategoryTheory.CategoryStruct.id (L'.obj X.left)) α).map
        (CategoryTheory.StructuredArrow.homMk f.right.left ⋯))
      { left := CategoryTheory.StructuredArrow.mk Z.hom.left, right := CategoryTheory.StructuredArrow.mk Z.hom.right,
          hom := CategoryTheory.StructuredArrow.homMk Z.right.hom ⋯ }.hom =
    CategoryTheory.CategoryStruct.comp
      { left := CategoryTheory.StructuredArrow.mk Y.hom.left, right := CategoryTheory.StructuredArrow.mk Y.hom.right,
          hom := CategoryTheory.StructuredArrow.homMk Y.right.hom ⋯ }.hom
      ((CategoryTheory.StructuredArrow.map₂ X.hom (CategoryTheory.inv β)).map
        (CategoryTheory.StructuredArrow.homMk f.right.right ⋯))