docs: def report_progress(self):
          """
          This function can be called from a higher level to report progress. It is usually called from an alarm
          signal handler which is installed just before starting an operation:
  
          :return: Tuple: (process description, #records, #total records, #rate)
          """
          from time import time
  
          # rows, rate = pl.sink.report_progress()
          return (self.i, round(float(self.i) / float(time() - self._start_time), 2))