∀ {ι : Type u_1} {𝕜 : Type u_2} [inst : NontriviallyNormedField 𝕜] {n : WithTop ℕ∞} {H : Type u_3}
  [inst_1 : TopologicalSpace H] {E : Type u_4} [inst_2 : NormedAddCommGroup E] [inst_3 : NormedSpace 𝕜 E]
  {I : ModelWithCorners 𝕜 E H} {G : Type u_5} [inst_4 : CommMonoid G] [inst_5 : TopologicalSpace G]
  [inst_6 : ChartedSpace H G] [ContMDiffMul I n G] {E' : Type u_6} [inst_8 : NormedAddCommGroup E']
  [inst_9 : NormedSpace 𝕜 E'] {H' : Type u_7} [inst_10 : TopologicalSpace H'] {I' : ModelWithCorners 𝕜 E' H'}
  {M : Type u_8} [inst_11 : TopologicalSpace M] [inst_12 : ChartedSpace H' M] {t : Finset ι} {f : ι → M → G},
  (∀ i ∈ t, ContMDiff I' I n (f i)) → ContMDiff I' I n (∏ i ∈ t, f i)