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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 _update_content(sender, instance, created=None, **kwargs):
 """ Re-save any content models referencing the just-modified ``FileUpload``. We don't do anything special to the content model, we just re-save it. If signals are in use, we assume that the content model has incorporated ``render_uploads`` into some kind of rendering that happens automatically at save-time. """

    if created: # a brand new FileUpload won't be referenced
        return
    for ref in FileUploadReference.objects.filter(upload=instance):
        try:
            obj = ref.content_object
            if obj:
                obj.save()
        except AttributeError:
            pass