∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {X Y : C} (f : X ⟶ Y)
  [inst_1 : CategoryTheory.Limits.HasPullbacksAlong f] (g : CategoryTheory.Over Y) {h : CategoryTheory.Over Y}
  {k : g ⟶ h},
  CategoryTheory.CategoryStruct.comp
      (CategoryTheory.Limits.pullback.lift
        (CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.pullback.fst g.hom f) k.left)
        (CategoryTheory.Limits.pullback.snd g.hom f) ⋯)
      (CategoryTheory.Over.mk (CategoryTheory.Limits.pullback.snd h.hom f)).hom =
    (CategoryTheory.Over.mk (CategoryTheory.Limits.pullback.snd g.hom f)).hom