∀ {𝕜 : Type u} [inst : NontriviallyNormedField 𝕜] {F : Type v} [inst_1 : NormedAddCommGroup F]
  [inst_2 : NormedSpace 𝕜 F] {f : 𝕜 → F} {x : 𝕜}, fderiv 𝕜 f x = ContinuousLinearMap.toSpanSingleton 𝕜 (deriv f x)