∀ {C₁ : Type u₁} {C₂ : Type u₂} {C₃ : Type u₃} [inst : CategoryTheory.Category.{v₁, u₁} C₁]
  [inst_1 : CategoryTheory.Category.{v₂, u₂} C₂] [inst_2 : CategoryTheory.Category.{v₃, u₃} C₃]
  {G : CategoryTheory.Functor C₁ᵒᵖ (CategoryTheory.Functor C₃ C₂)} {f₁ : CategoryTheory.Arrow C₁}
  {f₃ f₃' : CategoryTheory.Arrow C₃} (sq₁₃ : G.PullbackObjObj f₁.hom f₃.hom) (sq₁₃' : G.PullbackObjObj f₁.hom f₃'.hom)
  {f₃'' : CategoryTheory.Arrow C₃} (sq₁₃'' : G.PullbackObjObj f₁.hom f₃''.hom) (sq : f₃ ⟶ f₃') (sq' : f₃' ⟶ f₃''),
  CategoryTheory.CategoryStruct.comp (sq₁₃.mapArrowRight sq₁₃' sq) (sq₁₃'.mapArrowRight sq₁₃'' sq') =
    sq₁₃.mapArrowRight sq₁₃'' (CategoryTheory.CategoryStruct.comp sq sq')