∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  (S : CategoryTheory.ShortComplex C),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.CategoryStruct.id S.X₂) S.g =
    CategoryTheory.CategoryStruct.comp S.g (CategoryTheory.CategoryStruct.id S.X₃)