计数

转自：http://safehammad.com/downloads/python-idioms-2014-01-16.pdf

# GOOD

names = ['Safe', 'George', 'Mildred']

for i, name in enumerate(names):

　　print(i, name) # 0 Safe, 1 George etc.

# NOT SO GOOD

names = ['Safe', 'George', 'Mildred']

count = 0

for name in names:

　　print(name) # 0 Safe, 1 George etc.

　　count += 1