>>> from sets import Set
>>> engineers = Set(['John', 'Jane', 'Jack', 'Janice'])
>>> programmers = Set(['Jack', 'Sam', 'Susan', 'Janice'])
>>> management = Set(['Jane', 'Jack', 'Susan', 'Zack'])
>>> employees = engineers | programmers | management           # union
>>> engineering_management = engineers & programmers           # intersection
>>> fulltime_management = management - engineers - programmers # difference
>>> engineers.add('Marvin')                                    # add element
>>> print engineers
Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack'])
>>> employees.issuperset(engineers)           # superset test
False
>>> employees.update(engineers)               # update from another set
>>> employees.issuperset(engineers)
True
>>> for group in [engineers, programmers, management, employees]:
...     group.discard('Susan')                # unconditionally remove element
...     print group
...
Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack'])
Set(['Janice', 'Jack', 'Sam'])
Set(['Jane', 'Zack', 'Jack'])
Set(['Jack', 'Sam', 'Jane', 'Marvin', 'Janice', 'John', 'Zack'])