rfl
case h.refine_2
t : ℝ
f : ℂ → ℂ
diff : ∀ (σ : ℝ), DifferentiableAt ℂ f (↑σ + ↑t * I)
σ : ℝ
this : deriv (f ∘ fun σ => ↑σ + ↑t * I) σ = deriv f (↑σ + ↑t * I)
⊢ deriv (fun {σ₂} => f (↑σ₂ + ↑t * I)) σ = deriv (f ∘ fun σ => ↑σ + ↑t * I) σ
no goals