code: def flag_time_err(phase_err, time_thresh=0.02):
      
      time_err = []
      for stamp in phase_err:
          if abs(stamp[1]) > time_thresh:
              time_err.append(stamp[0])
      return time_err
docs: Find large time errors in list.
  
      Scan through a list of tuples of time stamps and phase errors
      and return a list of time stamps with timing errors above a threshold.
  
      .. note::
          This becomes important for networks cross-correlations, where
          if timing information is uncertain at one site, the relative arrival
          time (lag) will be incorrect, which will degrade the cross-correlation
          sum.
  
      :type phase_err: list
      :param phase_err: List of Tuple of float, datetime.datetime
      :type time_thresh: float
      :param time_thresh: Threshold to declare a timing error for
  
      :returns: List of :class:`datetime.datetime` when timing is questionable.