∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C] {J : Type u_3}
  [inst_2 : Fintype J] {f : J → C} (b : CategoryTheory.Limits.Bicone f)
  (s : CategoryTheory.Limits.Cocone (CategoryTheory.Discrete.functor f)) (j : CategoryTheory.Discrete J),
  CategoryTheory.CategoryStruct.comp (b.toCocone.ι.app j)
      (∑ j, CategoryTheory.CategoryStruct.comp (b.π j) (s.ι.app { as := j })) =
    s.ι.app j