∀ (C : Type u_2) [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.HasShift C ℤ]
  [inst_2 : CategoryTheory.Limits.HasZeroObject C] [inst_3 : CategoryTheory.Limits.HasZeroMorphisms C] (X : C),
  { hom₁ := CategoryTheory.CategoryStruct.id X, hom₂ := CategoryTheory.CategoryStruct.id X, hom₃ := 0, comm₁ := ⋯,
      comm₂ := ⋯, comm₃ := ⋯ } =
    CategoryTheory.CategoryStruct.id (CategoryTheory.Pretriangulated.contractibleTriangle X)