code: def _extract_rows(self, rows):
          
          if rows is not None:
              rows = numpy.array(rows, ndmin=1, copy=False, dtype='i8')
              # returns unique, sorted
              rows = numpy.unique(rows)
  
              maxrow = self._info['nrows']-1
              if rows[0] < 0 or rows[-1] > maxrow:
                  raise ValueError("rows must be in [%d,%d]" % (0, maxrow))
          return rows
docs: Extract an array of rows from an input scalar or sequence