Variable Arguments

[Jethro via Digitalmars-d-learn]

void foo(A...)(A a)
{
     foreach(aa; a)
     {
         for(int i = 0; i < a.length; i++)
             ...
     }
}

A can be strings or char, how can I easily deal with both? (e.g., 
a.length = 1 for a being a char... and also a[0] = a, so to 
speak).

That is, I want chars to be treated as strings of length 1, since 
I have written my code to work with strings, no reason it 
shouldn't work with chars. I realize we can't use the above 
notation but I can't get the type of aa because D complains it is 
unknown at compile time. I could use A[k] but it requires extra 
work.