Volta brackets in scores?

[Yotam Medini]

> > 3rd try:
> > 
> > \score { \notes\context Staff {
> > \property Staff.VoltaBracket = #'((meta .  ((interfaces . ()))))
> >  \repeat volta 2 { c4 c4 } \alternative { d4 e4 }  }}
> 
> Great, it works! How about adding a definition
> 
> turnOff = #'((meta .  ((interfaces . ()))))
> 
> in property.ly, so you could do 
> 
> \property Staff.VoltaBracket = \turnOff

Well, for me it does not work (yet?). I probbaly misuse it. 
Currently I get:

  Interpreting music...warning: 
    Can't find property type-check for `VoltaBracket'.  
    Perhaps you made a typing error?

Could someone put the above magic setting within a real example.
Using it in  star-spangled-banner.ly  would be a good place.
Both for a reference and making it look nicer.

thanks -- yotam