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

[aberba]

On Saturday, 25 July 2020 at 01:23:18 UTC, Mike Parker wrote:
> 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

Watched a video and they were also struggling to figure out what 
! means as it's used right at the beginning.

Could we highlight what the "!" mean? ...kind of like how Adam 
explained it?

Especially when they've at that point not got to the templates 
section yet.