python 官方文档上的代码不能执行

Question

我的python版本为3.5，进入安装目录找到帮助文档。里面的例子，源代码为啥不能执行？

例如，3.2的新功能，threading模块。有下面代码

from threading import Barrier, Thread

def get_votes(site):
    ballots = conduct_election(site)
    all_polls_closed.wait()        # do not count until all polls are closed
    totals = summarize(ballots)
    publish(site, totals)

all_polls_closed = Barrier(len(sites))
for site in sites:
    Thread(target=get_votes, args=(site,)).start()

根本执行不了呀

Answer 1

3.2模块新功能，collections模块，有下面的代码

>>> tally = Counter(dogs=5, cats=3)
>>> tally.subtract(dogs=2, cats=8)      # regular subtraction
>>> tally
Counter({'dogs': 3, 'cats': -5})

也不能执行。但是我在这些操作前加collections.就可以了。变为下面这样子

import collections
tally = collections.Counter(dogs=5, cats=3)
tally.subtract(dogs=2, cats=8) # 减去
print(tally)