∀ {ι : Type u_1} {V : Type u} [inst : CategoryTheory.Category.{v, u} V]
  [inst_1 : CategoryTheory.Limits.HasZeroMorphisms V] {c : ComplexShape ι} {C₁ C₂ : HomologicalComplex V c}
  (f : C₁.Hom C₂) (i : ι),
  CategoryTheory.CategoryStruct.comp (f.f i) (C₂.dFrom i) = CategoryTheory.CategoryStruct.comp (C₁.dFrom i) (f.next i)