Python language changes that first shipped in something besides CPython?

[Larry Hastings]

I'm doing a talk at PyCon about changes to the Python language.  I'm 
wondering: are there any Python language changes that first shipped in 
an implementation of Python besides CPython?

The sort of answer I'm looking for: "set literals first shipped in 
Jython 2.2, six months before they shipped in CPython 2.3".  (Note that 
that specific answer is wrong in every important detail.)


/larry/