def __xor__(self, that):
return SortedSet(self._view ^ that)
def __sub__(self, that):
return SortedSet(self._view - that)
def __and__(self, that):
return SortedSet(self._view & that)
def __or__(self, that):
return SortedSet(self._view | that)
def keys(self):
return SortedSet(self._dict)
