What's that 'q' before '{' in this code?

[Adam D. Ruppe]

On Tuesday, 15 January 2019 at 17:52:35 UTC, Machine Code wrote:
> https://github.com/dlang/dmd/blob/master/src/dmd/compiler.d#L75

It is a string literal that must be made out of D code tokens.

In my blog this week, I talked about some code that uses them:

http://dpldocs.info/this-week-in-d/Blog.Posted_2019_01_14.html#the-generated-client

You can see how it syntax highlights as code, but is semantically 
a string. The code inside is passed to mixin, so this hybrid 
appearance works well.