Friendsnippets

 1 >>> l1 = [2,3]
 2 >>> l2 = [4,7,2,3,8,9]
 3 >>> S1, S2 = set(l1), set(l2)
 4 >>> S1
 5 set([2, 3])
 6 >>> S2
 7 set([2, 3, 4, 7, 8, 9])
 8 >>> S1 & S2
 9 set([2, 3])
10 >>> S1 | S2
11 set([2, 3, 4, 7, 8, 9])
12 >>> S1-S2
13 set([])
14 >>> S2-S1
15 set([8, 9, 4, 7])