参考文献：http://www.maixj.net/ict/python-docstring-16247

http://wiki.jikexueyuan.com/project/simple-python-course/example-seven-eight.html

docstring，编写代码，同时也能写出文档，保持代码和文档的一致。
docstring说白了就是一堆代码中的注释。
Python的docstring可以通过help函数直接输出一份有格式的文档。

编写test.py

def printMax(x, y):
    '''Prints the maximum of two numbers.

    The two values must be integers.'''
    x = int(x) # convert to integers, if possible
    y = int(y)

    if x > y:
         print (x, 'is maximum')
    else:
         print (y, 'is maximum')

printMax(3, 5)
print (printMax.__doc__)

命令行输入 help(test)

import test
5 is maximum
Prints the maximum of two numbers.

    The two values must be integers.

help(test)
Help on module test:

NAME
    test - Created on Sat Jun  2 19:05:08 2018

DESCRIPTION
    @author: linzhiwei02

FUNCTIONS
    printMax(x, y)
        Prints the maximum of two numbers.

        The two values must be integers.

FILE
    /Users/linzhiwei02/Desktop/test.py