joanne> python
Python 2.7.3 (default, Jul 24 2012, 10:05:38) 
[GCC 4.7.0 20120507 (Red Hat 4.7.0-5)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> s1 = set([1,3,6,9])
>>> s1
set([1, 3, 6, 9])
>>> s2 = set([1,2,3,4])
>>> s1 | s2
set([1, 2, 3, 4, 6, 9])
>>> s1 & s2
set([1, 3])
>>> s1.add(4)
>>> s1
set([1, 3, 4, 6, 9])
>>> s1.add(4)
>>> s1
set([1, 3, 4, 6, 9])
>>> s3 = ([4,4,4])
>>> s3
[4, 4, 4]
>>> s3 = set(s3)
>>> s3
set([4])
>>> s3.add(1)
>>> s3.add(20)
>>> s3.add(-3)
>>> s3
set([1, 4, -3, 20])
>>> s2 & s3
set([1, 4])
>>> s3 &= s2
>>> s3
set([1, 4])
>>> s2
set([1, 2, 3, 4])
>>> s1
set([1, 3, 4, 6, 9])
>>> s1.discard(4)
>>> s1
set([1, 3, 6, 9])
>>> s1 & s3
set([1])
>>> for x in s1:
...     print x,
... 
1 3 6 9
>>> print 4 in s1
False
>>> print 6 in s1
True
>>> s1.union(s3)
set([1, 3, 4, 6, 9])
>>> s1.discard(5)
>>> s1.remove(5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 5
>>>