∀ {𝕜 : Type u_1} [inst : NontriviallyNormedField 𝕜] {E : Type u_2} [inst_1 : NormedAddCommGroup E]
  [inst_2 : NormedSpace 𝕜 E] {F : Type u_3} [inst_3 : NormedAddCommGroup F] [inst_4 : NormedSpace 𝕜 F] {G : Type u_4}
  [inst_5 : NormedAddCommGroup G] [inst_6 : NormedSpace 𝕜 G] {f : E → F} (x : E) {s : Set E} {g : F → G} {t : Set F},
  DifferentiableWithinAt 𝕜 g t (f x) → DifferentiableWithinAt 𝕜 f s x → DifferentiableWithinAt 𝕜 (g ∘ f) (s ∩ f ⁻¹' t) x