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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 chain(request):
 """shows how the XmlQuerySetChain can be used instead of @toxml decorator"""

    bars = foobar_models.Bar.objects.all()
    bazs = foobar_models.Baz.objects.all()
    qsc = XmlQuerySetChain(bars, bazs)
    return HttpResponse(tree.xml(qsc), mimetype='text/xml')