∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C] {σ τ : Type}
  {S : σ → C} [inst_3 : CategoryTheory.Limits.HasBiproduct S] {T : τ → C}
  [inst_4 : CategoryTheory.Limits.HasBiproduct T] (f : ⨁ S ⟶ ⨁ T) [inst_5 : CategoryTheory.IsIso f],
  CategoryTheory.IsIso
    (CategoryTheory.CategoryStruct.comp (CategoryTheory.CategoryStruct.comp f (CategoryTheory.inv f)) f)