How to use the pgl.utils.mp_reader.multiprocess_reader function in pgl

def reader():
        """reader"""
        batch_info = list(
            node_batch_iter(
                node_index, node_label, batch_size=batch_size))
        block_size = int(len(batch_info) / num_workers + 1)
        reader_pool = []
        for i in range(num_workers):
            reader_pool.append(
                worker(batch_info[block_size * i:block_size * (i + 1)], graph,
                       graph_wrapper, samples))
        multi_process_sample = mp_reader.multiprocess_reader(
            reader_pool, use_pipe=True, queue_size=1000)
        r = parse_to_subgraph(multi_process_sample)
        return paddle.reader.buffered(r, 1000)

def reader():
        """reader"""
        batch_info = list(
            node_batch_iter(
                node_index, node_label, batch_size=batch_size))
        block_size = int(len(batch_info) / num_workers + 1)
        reader_pool = []
        for i in range(num_workers):
            reader_pool.append(
                worker(batch_info[block_size * i:block_size * (i + 1)], 
                       graph_wrapper, samples))
        multi_process_sample = mp_reader.multiprocess_reader(
            reader_pool, use_pipe=True, queue_size=1000)
        r = parse_to_subgraph(multi_process_sample)
        return paddle.reader.buffered(r, 1000)