∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y Z : C} {f : X ⟶ Z} {g : Y ⟶ Z}
  [inst_1 : CategoryTheory.Limits.HasPullback f g],
  CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.pullback.snd f g) g =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.pullback.fst f g) f