docs: def calculate_statistics(self, start, stop):
          """Starts the statistics calculation.
  
          :param start: The left limit of the time window in percent.
          :param stop: The right limit of the time window in percent.
  
          .. note::
  
              The calculation takes some time. Check the status byte to see when
              the operation is done. A running scan will be paused until the
              operation is complete.
  
          .. warning::
  
              The SR850 will generate an error if the active display trace is not
              stored when the command is executed.
  
          """
          cmd = 'STAT', Integer, Integer
          self._write(cmd, start, stop)