Yeah, of course, now try to build a real world application with it.

Aliases: https://docs.microsoft.com/en-us/dotnet/csharp/language-refe.... Support for those was only added in the last year or so to the dotnet/nuget/roslyn/whatever it is needed things to make it work. Microsoft's own documentation only documents how to use it for Visual Studio: too bad if you're using another IDE or the command line like you did above.