∀ {F : Type u_1} [inst : FunLike F UpperHalfPlane ℂ] (h : ℝ) (f : F),
  ModularFormClass.qExpansion h f =
    PowerSeries.mk fun m => (↑m.factorial)⁻¹ * iteratedDeriv m (SlashInvariantFormClass.cuspFunction h ⇑f) 0