>>> x = set('abcde')
>>> y = set('bdxyz')
>>> x
set(['a', 'c', 'b', 'e', 'd']) # 2.6 display format
>>> 'e' in x # Membership
True
>>> x – y # Difference
set(['a', 'c', 'e'])
>>> x | y # Union
set(['a', 'c', 'b', 'e', 'd', 'y', 'x', 'z'])
>>> x & y # Intersection
set(['b', 'd'])
>>> x ^ y # Symmetric difference (XOR)
set(['a', 'c', 'e', 'y', 'x', 'z'])
>>> x > y, x < y # Superset, subset
(False, False)