∀ {V : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} V] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms V]
  [inst_2 : CategoryTheory.Limits.HasZeroObject V] (C : ChainComplex V ℕ) (X : V)
  (f : { f // CategoryTheory.CategoryStruct.comp (C.d 1 0) f = 0 }),
  (fun φ => ⟨φ.f 0, ⋯⟩) ((fun f => HomologicalComplex.mkHomToSingle ↑f ⋯) f) = f