How do I get an object from the id()-identifier?

[Mats Sjoberg]

I know that I can get a unique identifier (usually the memory 
address) of a python object with the id() function, but how do
I get the object back if I only have this identifier? (This will
all of course happen in the same session, otherwise the objects
will already be removed by the garbage collection...)

Mats Sjöberg