∀ {A : Type u_4} [inst : CategoryTheory.Category.{u_1, u_4} A] {B : Type u_5}
  [inst_1 : CategoryTheory.Category.{u_2, u_5} B] {T : Type u_6} [inst_2 : CategoryTheory.Category.{u_3, u_6} T]
  (L : CategoryTheory.Functor A T) {R₁ R₂ : CategoryTheory.Functor B T} (i : R₁ ≅ R₂) (X : CategoryTheory.Comma L R₁),
  CategoryTheory.CategoryStruct.comp
      ((CategoryTheory.Comma.mapRight L i.hom).map
        (((CategoryTheory.Comma.mapRightId L R₁).symm ≪≫
                CategoryTheory.Comma.mapRightEq L (CategoryTheory.CategoryStruct.id R₁)
                    (CategoryTheory.CategoryStruct.comp i.hom i.inv) ⋯ ≪≫
                  CategoryTheory.Comma.mapRightComp L i.hom i.inv).hom.app
          X))
      (((CategoryTheory.Comma.mapRightComp L i.inv i.hom).symm ≪≫
              CategoryTheory.Comma.mapRightEq L (CategoryTheory.CategoryStruct.comp i.inv i.hom)
                  (CategoryTheory.CategoryStruct.id R₂) ⋯ ≪≫
                CategoryTheory.Comma.mapRightId L R₂).hom.app
        ((CategoryTheory.Comma.mapRight L i.hom).obj X)) =
    CategoryTheory.CategoryStruct.id ((CategoryTheory.Comma.mapRight L i.hom).obj X)