[OT] C# can do all the interpolated strings now

[WebFreak001]

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated#compilation-of-interpolated-strings

> Beginning with C# 10, when an interpolated string is used, the 
> compiler checks if the interpolated string is assigned to a 
> type that satisfies the interpolated string handler pattern

Usage example: 
https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/tutorials/interpolated-string-handler

What do you think of these extended interpolated string 
expressions? I think these would fit well into D, and could give 
some new motivation now that we have had our interpolated strings 
DIPs rejected once and withdrawn once.