Cast to original type each argument in template pack

[Andrey]

Hello,
I have a function:
> string format(string pattern, T...)(T value)
>{
>    auto writer = appender!string();
>    
> writer.formattedWrite!pattern(convertToUnderlyingType(value)); 
> //Tuple!T(value).expand.to!(OriginalType!T)
> 
>    return writer.data;
>}

The "value" in this function can be any type including "enum". 
And if it is a "enum" I want to print it's contents not name.
So what I need - check if current argument in template pack is 
enum then convert it in original type. If current argument isn't 
enum - leave it as is. In my example I showed it with imaginary 
function "convertToUnderlyingType".
How to implement it in D?