遍历字典
d = {'x': 1, 'y': 2, 'z': 3}
遍历keys
for key in d:
print key,
y x z
for key in d.iterkeys():...d
print key,
y x z
for key in d.keys():
# d.keys() -> ['y', 'x', 'z']
print key,
y x z
遍历...print value,
2 1 3
for value in d.values():
# d.values() -> [2, 1, 3]
print value,
2 1 3
遍历