python3.6 f-string字符串格式化

https://www.cnblogs.com/traditional/p/9217594.html

https://mlln.cn/2018/05/19/python3%20f-string%E6%A0%BC%E5%BC%8F%E5%8C%96%E5%AD%97%E7%AC%A6%E4%B8%B2%E7%9A%84%E9%AB%98%E7%BA%A7%E7%94%A8%E6%B3%95/

https://blog.csdn.net/sunxb10/article/details/81036693

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