Review of std.signal

[Daniel Kozak]

On Thursday, 7 November 2013 at 13:45:57 UTC, Dicebot wrote:
> Time to move forward with some more reviews :)
>
> Our current victim is std.signal by Robert Klotzner which is 
> supposed to deprecate and supersede existing (and broken) 
> std.signals
>
Just one question. When I looked on code I noticed this part of 
code:
private:
     RestrictedSignal!(Args) restricted_;

And first what came to my mind was that I do not know restricted 
keyword. But than I find out there is no such keyword. So why is 
there a underscore at the end instead of at the beginning?