∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.HasShift C ℤ]
  [inst_2 : CategoryTheory.Preadditive C] [inst_3 : ∀ (n : ℤ), (CategoryTheory.shiftFunctor C n).Additive]
  (P Q R : CategoryTheory.Pretriangulated.Triangle C) (f f' : P ⟶ Q) (g : Q ⟶ R),
  CategoryTheory.CategoryStruct.comp (f + f') g =
    CategoryTheory.CategoryStruct.comp f g + CategoryTheory.CategoryStruct.comp f' g