2460         it = self._subset.fastdesc

  2460         it = self._subset.fastdesc

  2461         if it is None:

  2461         if it is None:

  2462             return None

  2462             return None

  2463         return lambda: self._iterfilter(it())

  2463         return lambda: self._iterfilter(it())

  2464 

  2464 

  2468     def __sub__(self, x):

  2465     def __sub__(self, x):

  2469         return filteredset(self, lambda r: r not in x)

  2466         return filteredset(self, lambda r: r not in x)

  2470 

  2467 

  2471     def __add__(self, x):

  2468     def __add__(self, x):

  2472         return _addset(self, x)

  2469         return _addset(self, x)