∀ {C : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  {K L : CochainComplex C ℤ} (φ : K ⟶ L) [inst_2 : CategoryTheory.Limits.HasZeroObject C]
  [inst_3 : ∀ (i : ℤ), HomologicalComplex.HasHomology K i] [inst_4 : ∀ (i : ℤ), HomologicalComplex.HasHomology L i]
  (n : ℤ) {Z : CochainComplex C ℤ} (h : L ⟶ Z),
  CategoryTheory.CategoryStruct.comp (CochainComplex.truncLEMap φ n)
      (CategoryTheory.CategoryStruct.comp (L.ιTruncLE n) h) =
    CategoryTheory.CategoryStruct.comp (K.ιTruncLE n) (CategoryTheory.CategoryStruct.comp φ h)