def cas(self, key, value, time=0, min_compress_len=0, namespace=None):
    return self._set_with_policy(MemcacheSetRequest.CAS, key, value,
                                 time, namespace)
Compare-And-Set update.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/memcache/__init__.py/Client.cas