[C#6.0]新語法

先筆記一下
1.nameof 表示式
2.字串插值 
3.Null 條件運算子

請參考
https://www.huanlintalk.com/2015/01/csharp6-enhanced-expressions.html
https://docs.microsoft.com/zh-tw/dotnet/csharp/language-reference/keywords/nameof
https://docs.microsoft.com/zh-tw/dotnet/csharp/tutorials/string-interpolation
https://docs.microsoft.com/zh-tw/dotnet/csharp/language-reference/operators/null-conditional-operators