def start(self):
        if not self._expiry_ms:
            # Don't bother starting the loop if things never expire
            return

        def f():
            self._prune_cache()

        self._clock.looping_call(f, self._expiry_ms / 2)
dataset/ETHPy150Open matrix-org/synapse/synapse/util/caches/expiringcache.py/ExpiringCache.start/original