∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C]
  {S : CategoryTheory.ShortComplex Cᵒᵖ} (h : S.Splitting),
  (CategoryTheory.CategoryStruct.comp h.s.unop S.unop.f + CategoryTheory.CategoryStruct.comp S.unop.g h.r.unop).op =
    (CategoryTheory.CategoryStruct.id S.unop.X₂).op