def average(values):
  """Computes the arithmetic mean of a list of numbers.

  > print(average([20, 30, 70]))
  40.0
  """
  return sum(values) / len(values)


#
if __name__ == '__main__':
  import doctest
  doctest.testmod(verbose=True) # automatically validate the embedded tests
  # 那个verbose参数，如果设置为True则在执行测试的时候会输出详细信息。
  # 默认是False，表示运行测试时，只有失败的用例会输出详细信息，成功的测试用例不会输入任何信息。

"help", "copyright", "credits" or "license" for more information.

> import os

> os.getcwd()
'/Users/dengjiguang/PycharmProjects/ForF'
> os.chdir('/Users/dengjiguang/PycharmProjects/ForF'+'/python_sample/quality_control')

> os.system('python3 -m doctest doctest_q.py -v')
Trying:
  print(average([20, 30, 70]))
Expecting:
  40.0
ok
1 items had no tests:
  doctest_q
1 items passed all tests:
  1 tests in doctest_q.average
1 tests in 2 items.
1 passed and 0 failed.
Test passed.
0
>