code: def centerdc_gen(self):
          
          for a in range(0, self.N):
              yield (a-self.N/2) * self.df
docs: Return the centered frequency range as a generator.
  
          ::
  
              >>> print(list(Range(8).centerdc_gen()))
              [-0.5, -0.375, -0.25, -0.125, 0.0, 0.125, 0.25, 0.375]