code: def nonparabolicity(self, **kwargs):
          '''
          Returns the Kane band nonparabolicity parameter for the Gamma-valley.
          '''
          Eg = self.Eg_Gamma(**kwargs)
          meff = self.meff_e_Gamma(**kwargs)
          T = kwargs.get('T', 300.)
          return k*T/Eg * (1 - meff)**f nonparabolicity(self, **kwargs):
          '''
          Returns the Kane band nonparabolicity parameter for the Gamma-valley.
          '''
          Eg = self.Eg_Gamma(**kwargs)
          meff = self.meff_e_Gamma(**kwargs)
          T = kwargs.get('T', 300.)
          return k*T/Eg * (1 - meff)**2
docs: Returns the Kane band nonparabolicity parameter for the Gamma-valley.