Proof of concept for v2 - NO duplication, NO `static if` hell, NO difficulty with interoperability

[zjh]

On Friday, 31 December 2021 at 01:58:12 UTC, zjh wrote:

>> `...` is a very powerful feature.

`C++` write like this:
```d
template<class T,class...O>
void g(T&a,O&...o){
     (f(o,a),...);
}
```
you don't need to iterate arrays such, `very convient`.