∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C] {X Y : C}
  {t : CategoryTheory.Limits.Cone (CategoryTheory.Limits.pair X Y)} (ht : CategoryTheory.Limits.IsLimit t),
  CategoryTheory.CategoryStruct.comp
      (ht.lift (CategoryTheory.Limits.BinaryFan.mk 0 (CategoryTheory.CategoryStruct.id Y)))
      (t.π.app { as := CategoryTheory.Limits.WalkingPair.left }) =
    0