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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def treenav_undefined_url(request, item_slug):
 """ Sample view demonstrating that you can provide custom handlers for undefined menu items on a per-item basis. """

    item = get_object_or_404(treenav.MenuItem, slug=item_slug)  # noqa
    # do something with item here and return an HttpResponseRedirect
    raise Http404