∀ {𝕜 : Type u} [inst : NontriviallyNormedField 𝕜] {F : Type v} [inst_1 : AddCommGroup F] [inst_2 : Module 𝕜 F]
  [inst_3 : TopologicalSpace F] {f : 𝕜 → F} {x : 𝕜} {s : Set 𝕜}, ¬DifferentiableWithinAt 𝕜 f s x → derivWithin f s x = 0