How to use the queuelib.queue.FifoMemoryQueue function in queuelib

def _pickle_serialize(obj):
    try:
        return pickle.dumps(obj, protocol=2)
    except pickle.PicklingError as e:
        raise ValueError(str(e))

PickleFifoDiskQueue = _serializable_queue(queue.FifoDiskQueue, \
    _pickle_serialize, pickle.loads)
PickleLifoDiskQueue = _serializable_queue(queue.LifoDiskQueue, \
    _pickle_serialize, pickle.loads)
MarshalFifoDiskQueue = _serializable_queue(queue.FifoDiskQueue, \
    marshal.dumps, marshal.loads)
MarshalLifoDiskQueue = _serializable_queue(queue.LifoDiskQueue, \
    marshal.dumps, marshal.loads)
FifoMemoryQueue = queue.FifoMemoryQueue
LifoMemoryQueue = queue.LifoMemoryQueue

def __init__(self):
        self.q = deque()
        self.push = self.q.append

    def pop(self):
        q = self.q
        return q.popleft() if q else None

    def close(self):
        pass

    def __len__(self):
        return len(self.q)


class LifoMemoryQueue(FifoMemoryQueue):
    """In-memory LIFO queue, API compliant with LifoDiskQueue."""

    def pop(self):
        q = self.q
        return q.pop() if q else None


class FifoDiskQueue(object):
    """Persistent FIFO queue."""

    szhdr_format = ">L"
    szhdr_size = struct.calcsize(szhdr_format)

    def __init__(self, path, chunksize=100000):
        self.path = path
        if not os.path.exists(path):

# Python <= 3.4 raises pickle.PicklingError here while
    # 3.5 <= Python < 3.6 raises AttributeError and
    # Python >= 3.6 raises TypeError
    except (pickle.PicklingError, AttributeError, TypeError) as e:
        raise ValueError(str(e))


PickleFifoDiskQueue = _serializable_queue(queue.FifoDiskQueue,
    _pickle_serialize, pickle.loads)
PickleLifoDiskQueue = _serializable_queue(queue.LifoDiskQueue,
    _pickle_serialize, pickle.loads)
MarshalFifoDiskQueue = _serializable_queue(queue.FifoDiskQueue,
    marshal.dumps, marshal.loads)
MarshalLifoDiskQueue = _serializable_queue(queue.LifoDiskQueue,
    marshal.dumps, marshal.loads)
FifoMemoryQueue = queue.FifoMemoryQueue
LifoMemoryQueue = queue.LifoMemoryQueue