I don't know how worthy this is in the context of Parrot, but it's
worth taking a look at:

http://svn.openfoundry.org/pugs/misc/pX/Common/redsix/

-- 
If it's there, and you can see it, it's real.
If it's not there, and you can see it, it's virtual.
If it's there, and you can't see it, it's transparent.
If it's not there, and you can't see it, you erased it.