∀ {E : Type u_2} [inst : NormedAddCommGroup E] [inst_1 : NormedSpace ℂ E] {f : E → ℂ} {f' : StrongDual ℂ E} {x : E},
  HasStrictFDerivAt f f' x → f x ∈ Complex.slitPlane → HasStrictFDerivAt (fun t => Complex.log (f t)) ((f x)⁻¹ • f') x