∀ {C : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  (self : CategoryTheory.ShortComplex C) {Z : C} (h : self.X₃ ⟶ Z),
  CategoryTheory.CategoryStruct.comp self.f (CategoryTheory.CategoryStruct.comp self.g h) =
    CategoryTheory.CategoryStruct.comp 0 h