∀ {𝕜 : Type u_1} [inst : NontriviallyNormedField 𝕜] {H : Type u_2} [inst_1 : TopologicalSpace H] {E : Type u_3}
  [inst_2 : NormedAddCommGroup E] [inst_3 : NormedSpace 𝕜 E] {I : ModelWithCorners 𝕜 E H} {n : WithTop ℕ∞}
  {G : Type u_4} [inst_4 : Mul G] [inst_5 : TopologicalSpace G] [inst_6 : ChartedSpace H G] [ContMDiffMul I n G]
  {a b : G}, ContMDiffAt I I n (fun x => x * a) b