∀ {A : Type u_1} [inst : NonUnitalNormedRing A] [inst_1 : StarRing A] [inst_2 : NormedSpace ℝ A]
  [inst_3 : IsScalarTower ℝ A A] [inst_4 : SMulCommClass ℝ A A] [inst_5 : PartialOrder A] [inst_6 : StarOrderedRing A]
  [inst_7 : NonUnitalIsometricContinuousFunctionalCalculus ℝ A IsSelfAdjoint] [inst_8 : NonnegSpectrumClass ℝ A]
  {f : NNReal → NNReal} {a : A} {c : NNReal}, (∀ x ∈ quasispectrum NNReal a, f x < c) → ‖cfcₙ f a‖₊ < c