>>> s=set([1,2,3,4,5,1,2]) >>> s set([1, 2, 3, 4, 5]) >>> fs=frozenset(s) >>> fs frozenset([1, 2, 3, 4, 5]) >>> fs.issubset(s);fs.issuperset(s) True True >>> t=set([1,2,6,7,8,9]) >>> s.intersection(t), s&t (set([1, 2]), set([1, 2])) >>> s.union(t), s|t (set([1, 2, 3, 4, 5, 6, 7, 8, 9]), set([1, 2, 3, 4, 5, 6, 7, 8, 9])) >>> s.difference(t), s-t (set([3, 4, 5]), set([3, 4, 5])) >>> s.symmetric_difference >>> s.symmetric_difference(t), s^t (set([3, 4, 5, 6, 7, 8, 9]), set([3, 4, 5, 6, 7, 8, 9])) >>> s.copy() set([1, 2, 3, 4, 5]) >>> fs.copy() frozenset([1, 2, 3, 4, 5]) >>> r=s.copy() >>> r set([1, 2, 3, 4, 5]) >>> s.update(t), s|=t SyntaxError: illegal expression for augmented assignment >>> s.update(t); s|=t >>> s set([1, 2, 3, 4, 5, 6, 7, 8, 9]) >>> s.add(1) >>> s.add(44) >>> s set([1, 2, 3, 4, 5...