∀ {J : Type w} {C : Type u} [inst : CategoryTheory.Category.{v, u} C]
  [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C] {f g : J → C} [inst_2 : CategoryTheory.Limits.HasBiproduct f]
  [inst_3 : CategoryTheory.Limits.HasBiproduct g] (p : (j : J) → f j ⟶ g j) (j : J) {Z : C} (h : g j ⟶ Z),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.biproduct.map p)
      (CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.biproduct.π g j) h) =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.biproduct.π f j)
      (CategoryTheory.CategoryStruct.comp (p j) h)