∀ {ι : Type u_1} {M : Type u_3} {X : Type u_5} [inst : TopologicalSpace X] [inst_1 : TopologicalSpace M]
  [inst_2 : AddCommMonoid M] [ContinuousAdd M] {f : ι → X → M} (s : Multiset ι),
  (∀ i ∈ s, Continuous (f i)) → Continuous fun a => (Multiset.map (fun i => f i a) s).sum