The one thing you need to know for basic usage is how optparse behaves when it encounters an error on the command-line--e.g. -n 4x where -n is an integer-valued option. In this case, optparse prints your usage message to stderr, followed by a useful and human-readable error message. Then it terminates (calls sys.exit()) with a non-zero exit status.
If you don't like this, subclass OptionParser and override the error() method. See section 6.20.5, ``Extending optparse.''
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