Adding optional 'explicit' declaration?

[skip at pobox.com]

    Clarence> But even if typos (which cause NameErrors particularly) are
    Clarence> found the first time you run the program, which is often the
    Clarence> case, if the program runs for an hour before hitting the error
    Clarence> (which happened to me the other day), that's still an
    Clarence> annoyance.

Sounds like you might want to check out PyChecker (announced recently on
this group):

    test_input/test1.py:35 No global (sys) found

-- 
Skip Montanaro (skip at pobox.com)
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