∀ {α : Type u_1} {β : Type u_2} {ι : Type u_3} [inst : AddCommMonoid α] (f : ι → β → α) (s : Set β)
  [inst_1 : UniformSpace α] [inst_2 : TopologicalSpace β],
  SummableLocallyUniformlyOn f s = ∃ g, HasSumLocallyUniformlyOn f g s