code: def get_perturbation(ts, axis=-1):
      r
      slices = [slice(None)] * ts.ndim
      slices[axis] = None
      mean = ts.mean(axis=axis)[tuple(slices)]
      return ts - mean
docs: r"""Compute the perturbation from the mean of a time series.
  
      Parameters
      ----------
      ts : array_like
           The time series from which you wish to find the perturbation
           time series (perturbation from the mean).
  
      Returns
      -------
      array_like
          The perturbation time series.
  
      Other Parameters
      ----------------
      axis : int
             The index of the time axis. Default is -1
  
      Notes
      -----
      The perturbation time series produced by this function is defined as
      the perturbations about the mean:
  
      .. math:: x(t)^{\prime} = x(t) - \overline{x(t)}