docs: def powerspec(data, tbin, Df=None, units=False, pointProcess=False):
      """
      Calculate (smoothed) power spectra of all timeseries in data.
      If units=True, power spectra are averaged across units.
      Note that averaging is done on power spectra rather than data.
  
      If pointProcess is True, power spectra are normalized by the length T of the
      time series.
  
   
      Parameters
      ----------
      data : numpy.ndarray
          1st axis unit, 2nd axis time.
      tbin : float
          Binsize in ms.
      Df : float/None, 
          Window width of sliding rectangular filter (smoothing),
          None is no smoothing.
      units : bool
          Average power spectrum.
      pointProcess : bool
          If set to True, powerspectrum is normalized to signal length T.
  
  
      Returns
      -------
      freq : tuple
          numpy.ndarray of frequencies.
      POW : tuple
          if units=False: 
              2 dim numpy.ndarray; 1st axis unit, 2nd axis frequency
          if units=True:  
              1 dim numpy.ndarray; frequency series
  
      
      Examples
      --------    
      >>> powerspec(np.array([analog_sig1, analog_sig2]), tbin, Df=Df)
      Out[1]: (freq,POW)
      >>> POW.shape
      Out[2]: (2,len(analog_sig1))
  
      >>> powerspec(np.array([analog_sig1, analog_sig2]), tbin, Df=Df, units=True)
      Out[1]: (freq,POW)
      >>> POW.shape
      Out[2]: (len(analog_sig1),)
  
      """
  
      freq, DATA = calculate_fft(data, tbin)
      df = freq[1] - freq[0]
      T = tbin * len(freq)
      POW = np.abs(DATA) ** 2
      if Df is not None:
          POW = [movav(x, Df, df) for x in POW]
          cut = int(Df / df)
          freq = freq[cut:]
          POW = np.array([x[cut:] for x in POW])
          POW = np.abs(POW)
      assert(len(freq) == len(POW[0]))
      if units is True:
          POW = mean(POW, units=units)
          assert(len(freq) == len(POW))
      if pointProcess:
          POW *= 1. / T * 1e3  # Normalization, power independent of T
      return freq, POW