1抛出异常

raise Exception('xxxxxx')

2抓捕异常

try:
  pass
except Exception as err:#保存在err的变量之中
  print('xxx'+str(err))
finally:
  pass

3取得反向跟踪的字符串

import traceback
try:
    raise Exception('Error')
except:
    errorFile = open(path, 'w')
    errorFile.write(traceback.format_exc())
    errorFile.close()
    print('The traceback info was written to errorInfo.txt')

4断言

assert ...

assert 'red' in stoplight.values(), 'Neither light is red!' + str(stoplight)

如何禁用？
$ python -O err.py

5日志

日志是个好东西

举个栗子：
如何调用日志？

import logging
import logging.basicConfig(filename = Path, 
                           level = logging.DEBUG, 
                           format = '%(asctime)s - %(levelname)s - %(message)s'
)
#前面是放在之前的
#logging.disable(logging.CRITICAL)
logging.debug('Start of xxxxx')
logging.info('xxxx')
logging.warning('xxxx')
logging.error('xxx')
logging.critical('xxxxx')

注意前面的filename，可以存入一个文档里，然后边看文档，边打代码。