How to use the pottery.ContextTimer function in pottery

def setUp(self):
        super().setUp()
        self.timer = ContextTimer()

def test_acquire_same_lock_twice_blocking_without_timeout(self):
        assert not self.redis.exists(self.redlock.key)
        with ContextTimer() as timer:
            assert self.redlock.acquire()
            assert self.redis.exists(self.redlock.key)
            assert self.redlock.acquire()
            assert self.redis.exists(self.redlock.key)
            assert timer.elapsed() >= self.redlock.auto_release_time