def warning(self, response):
        return '110 - "Response is Stale"'
Returns the str serial number from system_profiler, or '' if not found.
dataset/ETHPy150Open ionrock/cachecontrol/cachecontrol/heuristics.py/BaseHeuristic.warning--crossover with--dataset/ETHPy150Open google/simian/src/simian/mac/client/flight_common.py/_GetSerialNumber