∀ {J : Type w} {C : Type u} [inst : CategoryTheory.Category.{v, u} C]
  [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C] (f : J → C) [inst_2 : CategoryTheory.Limits.HasBiproduct f]
  (j : J) {Z : C} (h : f j ⟶ Z),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.biproduct.ι f j)
      (CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.biproduct.π f j) h) =
    h