code: def zpk(self, zeros, poles, gain, analog=True, **kwargs):
          
          return self.filter(zeros, poles, gain, analog=analog, **kwargs)
docs: Filter this `TimeSeries` by applying a zero-pole-gain filter
  
          Parameters
          ----------
          zeros : `array-like`
              list of zero frequencies (in Hertz)
  
          poles : `array-like`
              list of pole frequencies (in Hertz)
  
          gain : `float`
              DC gain of filter
  
          analog : `bool`, optional
              type of ZPK being applied, if `analog=True` all parameters
              will be converted in the Z-domain for digital filtering
  
          Returns
          -------
          timeseries : `TimeSeries`
              the filtered version of the input data
  
          See Also
          --------
          TimeSeries.filter
              for details on how a digital ZPK-format filter is applied
  
          Examples
          --------
          To apply a zpk filter with file poles at 100 Hz, and five zeros at
          1 Hz (giving an overall DC gain of 1e-10)::
  
          >>> data2 = data.zpk([100]*5, [1]*5, 1e-10)