D lang newbie ..what does syntax func_name !() represent ??

[Mike Parker]

On Saturday, 25 July 2020 at 00:36:19 UTC, Andy Balba wrote:
> Hello forum
>  I'm a long-time C/C++ coder who recently completed the D lang 
> on-line tour and want to improve my D lang savy.
>
> I keep running into statements like  `func_name!()`
> and cant figure out what !() could possibly mean .
>
> Pz help, it's driving me nuts

https://dlang.org/spec/template.html