python内置的日志模块logging可以完成各种日志任务，方便记录软件运行情况，方便回溯。
import logging
import os
logging.basicConfig(level=logging.INFO, format='%(asctime)s-%(levelname)s : %(message)s')
logger = logging.getLogger(__name__)
logger.info("Start print log")
logger.debug("Do something")
logger.warning("Something maybe fail")
