用途enumerate：
#!/usr/bin/env python
d = {1:2, 3:4, 5:6, 7:8, 9:0}
# If you want an ordered dictionary (and have python 2.7/3.2),
# uncomment the next lines:
# from collections import OrderedDict
# d = OrderedDict(sorted(d.items(), key=lambda t: t[0]))
last = len(d) - 1
for i, x in enumerate(d):
if i == last:
print i, x, 'last'
else:
print i, x
# Output:
# 0 1
# 1 3
# 2 9
# 3 5
# 4 7 last
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