python - ex: Fix breakage cause by previous commit.

Log Message:
-----------
Fix breakage cause by previous commit. The code keyword overloaded the global
code. Just import it as another name for now. (Shouldn't be too expensive).

Modified Files:
--------------
ex/src:
prime.py (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/ex/src/prime.py.diff?r1=1.5&r2=1.6)