C#6.0:
https://www.cnblogs.com/yinrq/p/5600530.html
C#7.0:
https://www.cnblogs.com/cncc/p/7698543.html
C#8.0:
https://www.cnblogs.com/SavionZhang/p/11201818.html
C#9.0:
https://www.cnblogs.com/CoderAyu/archive/2019/06/10/11000386.html
ValueTuple:
https://www.cnblogs.com/zhoufangcheng04050227/p/11122847.html
デフォルトのインタフェース:
https://www.cnblogs.com/Rwing/p/default-implementations-in-interfaces.html