code: def _slice2rows(self, start, stop, step=None):
          
          nrows = self._info['nrows']
          if start is None:
              start = 0
          if stop is None:
              stop = nrows
          if step is None:
              step = 1
  
          tstart = self._fix_range(start)
          tstop = self._fix_range(stop)
          if tstart == 0 and tstop == nrows:
              # this is faster: if all fields are also requested, then a
              # single fread will be done
              return None
          if stop < start:
              raise ValueError("start is greater than stop in slice")
          return numpy.arange(tstart, tstop, step, dtype='i8')
docs: Convert a slice to an explicit array of rows