code: def _reversebytes(self, start, end):
          
          # Make the start occur on a byte boundary
          # TODO: We could be cleverer here to avoid changing the offset.
          newoffset = 8 - (start % 8)
          if newoffset == 8:
              newoffset = 0
          self._datastore = offsetcopy(self._datastore, newoffset)
          # Now just reverse the byte data
          toreverse = bytearray(self._datastore.getbyteslice((newoffset + start) // 8, (newoffset + end) // 8))
          toreverse.reverse()
          self._datastore.setbyteslice((newoffset + start) // 8, (newoffset + end) // 8, toreverse)
docs: Reverse bytes in-place.