I have just quickly pasted it into an interpreter.

Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> class Node(object):
...     pass
...
>>> nodes = [Node() for i in range(500)]
>>> for n in nodes:
...     n.connections = list(nodes)
...     n.connections.remove(n)
...
>>> import cPickle
>>> s = cPickle.dumps( n )

After this line, the interpreter terminated without any further output
(no Python exception and no Windows "General Exception" message box either).

Is it sufficient, or would you prefer me to run the test properly?