How to declare function with the same call signature as another?

[Nicholas Wilson via Digitalmars-d-learn]

On Sunday, 20 November 2016 at 11:19:24 UTC, Tofu Ninja wrote:
> I feel like this should be simple but I can't seem to figure it 
> out. How do I declare a function to have the same call 
> signature as another function/callable type?
>
> Like if I have:
>
> alias Sig = int function(int x, int y);
>
> How do I define a function such that it will have the same call 
> signature as Sig? How do I take into account all the extra 
> stuff that can go into a function signature like the argument 
> attributes and the return type attributes etc.?
>
> Another way to phrase this question would be, how do I pass a 
> function signature into a template and actually define 
> functions with it?
>
> Related question, if I have Sig, how would I define DeltaSig to 
> be exactly the same as Sig but with an extra parameter at the 
> start or end of the parameter list?
>
> Thanks :)

Or if you want additional parameters.

ReturnType!Sig func(int paramBefore, Parameters!Sig args, int 
paramAfter) { ... }