How can you read and understand the source of *naryFun in functional.d?

[Tom]

I would like to thank you for that such a great explanation of the Template-based
programming in that unary example. I think it's great you have uploaded that to
the wiki4d, and it's definite will help a lot of people that come from other
common languages background (like C, C# and Python) that don't support full
templating, to understand that design pattern.
And with that close tracking to the functional.d code, I thing but not sure that
we've found some bugs. I will do some testing later today, and if I will see what
I think to be wrong, I'll update.

and again,
 Thanks