∀ {C : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} C] [inst_1 : CategoryTheory.Preadditive C]
  {S₁ S₂ : CategoryTheory.ShortComplex C} (φ₁ φ₂ : S₁ ⟶ S₂) (h : CategoryTheory.ShortComplex.Homotopy φ₁ φ₂),
  (CategoryTheory.ShortComplex.Homotopy.equivSubZero φ₁ φ₂) h =
    (h.sub (CategoryTheory.ShortComplex.Homotopy.refl φ₂)).trans (CategoryTheory.ShortComplex.Homotopy.ofEq ⋯)