docs: def str_rate(self):
          """Returns the rate with formatting. If done, returns the overall rate instead."""
          # Handle special cases.
          if not self._eta.started or self._eta.stalled or not self.rate:
              return '--.-KiB/s'
  
          unit_rate, unit = UnitByte(self._eta.rate_overall if self.done else self.rate).auto
          if unit_rate >= 100:
              formatter = '%d'
          elif unit_rate >= 10:
              formatter = '%.1f'
          else:
              formatter = '%.2f'
          return '{0}{1}/s'.format(locale.format(formatter, unit_rate, grouping=False), unit)