# .. snip ..
        auth = HttpAuthenticated(username = username, password = password)
        req = Request(self.url)
        try:
            auth.open(req)
        except suds.transport.TransportError as (err):
            print "TransportError: " + str(err.args)
            sys.exit(1)
# .. snip ..

# Outputs this:

# TransportError: ('HTTP Error 401: Unauthorized',)