code: def cyclic_time_shift(self, dt):
          
          from pycbc.waveform import apply_fseries_time_shift
          data = apply_fseries_time_shift(self, dt)
          data.start_time = self.start_time - dt
          return data
docs: Shift the data and timestamps by a given number of seconds
  
          Shift the data and timestamps in the time domain a given number of 
          seconds. To just change the time stamps, do ts.start_time += dt. 
          The time shift may be smaller than the intrinsic sample rate of the data.
          Note that data will be cycliclly rotated, so if you shift by 2
          seconds, the final 2 seconds of your data will now be at the 
          beginning of the data set.
  
          Parameters
          ----------
          dt : float
              Amount of time to shift the vector.
  
          Returns
          -------
          data : pycbc.types.FrequencySeries
              The time shifted frequency series.