code: def chain(request):
      
      bars = foobar_models.Bar.objects.all()
      bazs = foobar_models.Baz.objects.all()
      qsc = XmlQuerySetChain(bars, bazs)
      return HttpResponse(tree.xml(qsc), mimetype='text/xml')
docs: shows how the XmlQuerySetChain can be used instead of @toxml decorator