code: def _join(self, rows):
      '''
      Join multiple rows worth of data into a single result.
      '''
      rval = {}
      for row in rows:
        if row:
          for value,count in row.items():
            rval[ value ] = count + rval.get(value,0)
      return rvaf _join(self, rows):
      '''
      Join multiple rows worth of data into a single result.
      '''
      rval = {}
      for row in rows:
        if row:
          for value,count in row.items():
            rval[ value ] = count + rval.get(value,0)
      return rval
docs: Join multiple rows worth of data into a single result.