∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C]
  {S₁ S₂ : CategoryTheory.ShortComplex C} {φ₁ φ₂ φ₃ : S₁ ⟶ S₂} (h₁₂ : CategoryTheory.ShortComplex.Homotopy φ₁ φ₂)
  (h₂₃ : CategoryTheory.ShortComplex.Homotopy φ₂ φ₃), CategoryTheory.CategoryStruct.comp S₁.g (h₁₂.h₃ + h₂₃.h₃) = 0