∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.Preadditive C]
  [inst_2 : CategoryTheory.Limits.HasZeroObject C] [inst_3 : CategoryTheory.HasShift C ℤ]
  [inst_4 : ∀ (n : ℤ), (CategoryTheory.shiftFunctor C n).Additive] [inst_5 : CategoryTheory.Pretriangulated C]
  (t : CategoryTheory.Triangulated.TStructure C) (a b : ℤ) (h : a ≤ b) (j : C),
  ((t.triangleLTLTGELT a b h).obj j).mor₃ =
    CategoryTheory.CategoryStruct.comp ((t.truncGEδLT a).app ((t.truncLT b).obj j))
      ((CategoryTheory.shiftFunctor C 1).map ((t.truncLT a).map ((t.truncLTι b).app j)))