pdb

core code:

import pdb
pdb.set_trace()

单步执行并进入：s

单步执行并不进入：n

下一断点：c

当前位置：where

从当前函数返回：r

退出：q

pdb commands:

https://www.ibm.com/developerworks/cn/linux/l-cn-pythondebugger/index.html

you can get the value of code by  directly copy the code and enter!!!

offical document:

https://docs.python.org/2/library/pdb.html

https://docs.python.org/3/library/pdb.html