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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 build_absolute_uri(request, url):
 """ Allow to override printing url, not necessarily on the same server instance. """

    if app_settings.get('CAPTURE_ROOT_URL'):
        return urljoin(app_settings.get('CAPTURE_ROOT_URL'), url)
    return request.build_absolute_uri(url)