refine And.intro (differentiable_fourierIntegral f) ?_
case hsuc
F : Type u_1
inst✝² : NormedAddCommGroup F
inst✝¹ : NormedSpace ℂ F
inst✝ : CompleteSpace F
n : ℕ
IH : ∀ (f : 𝓢(ℝ, F)), ContDiff ℝ ↑n fun ξ => 𝓕 (fun x => f x) ξ
f : 𝓢(ℝ, F)
⊢ (Differentiable ℝ fun ξ => 𝓕 (fun x => f x) ξ) ∧ ContDiff ℝ (↑n) (deriv fun ξ => 𝓕 (fun x => f x) ξ)
case hsuc
F : Type u_1
inst✝² : NormedAddCommGroup F
inst✝¹ : NormedSpace ℂ F
inst✝ : CompleteSpace F
n : ℕ
IH : ∀ (f : 𝓢(ℝ, F)), ContDiff ℝ ↑n fun ξ => 𝓕 (fun x => f x) ξ
f : 𝓢(ℝ, F)
⊢ ContDiff ℝ (↑n) (deriv fun ξ => 𝓕 (fun x => f x) ξ)