what is the keyword "is" for?

[Terry Reedy]

"Sybren Stuvel" <sybrenUSE at YOURthirdtower.com.imagination> wrote in message 
news:slrnee2sqi.qt8.sybrenUSE at schuimige.stuvel.eu...
> 'is' compares the object's addresses.

It actually compares the objects' integer identifiers.  That happens to be 
the linear memory address for CPython, but not necesarily so for other 
interpreters.

tjr