异常：
class createItenError(Exception)
raise createItenError("test test")
try
xxxxcccc
except createItenError as e:
print(f(‘create item fail: {err_msg}’））
yield 生成器
docttest
unittest
参考：
http://www.iwebscraper.com/
pandas性能优化
https://blog.csdn.net/sinat_38682860/article/details/85046081
https://blog.csdn.net/mutex86/article/details/79670034
https://blog.csdn.net/qq_37509235/article/details/80543904
plot 定义
https://www.cnblogs.com/onemorepoint/p/7482644.html
Queque
https://www.cnblogs.com/wongbingming/p/9035579.html
https://blog.csdn.net/liyuan_35023/article/details/50926895
https://blog.csdn.net/liyuan_35023/article/details/50947918
https://blog.csdn.net/SHENNONGZHAIZHU/article/details/51556367
MQTT
https://blog.csdn.net/xukai871105/article/details/39255089
