∀ {𝕂 : Type u_1} {𝔸 : Type u_2} [inst : NontriviallyNormedField 𝕂] [inst_1 : NormedRing 𝔸] [inst_2 : NormedAlgebra 𝕂 𝔸],
  ∀ x ∈ Metric.eball 0 (NormedSpace.expSeries 𝕂 𝔸).radius, Summable fun n => ‖(↑n.factorial)⁻¹ • x ^ n‖