diff between 2.2 and 2.3
minor difference between python 2.2 and 2.3
packages missing in 2.2 -- sets, heapq
error in 2.2 but not in 2.3 -- 'elif opt in ("-n"):' causes 'TypeError: 'in <string>' requires character as left operand'. 'elif opt in ("-n",):' is ok.
missing functions in 2.2 -- sum(), enumerate()
integer -- int and long are separate in python2.2, but same in python2.3.