code: def __init__(self, path="", prefix="train"):
      assert os.path.isdir(path)
  
      self.documents = []
      filename_list = os.listdir(path)
      for file in filename_list:
          path_to_file = os.path.join(path, file)
          if not os.path.isfile(path_to_file):
              continue
          self.documents.append(path_to_file)
  
imports: import re
  import torch
  import torch.nn
  import torch.nn.functional
  from torch.utils.data import Dataset, DataLoader, random_split
  from tqdm import tqdm
  from reformer_pytorch import Reformer, ReformerLM
  from transformers import BertTokenizer, PreTrainedTokenizer
  from fairseq.optim.adafactor import Adafactor
  import os
  import json
  import logging
  from datetime import datetime
label_desc: Use image node_id 1 to create a new WikiDataset object from inherited base classes: Dataset with example: obj = WikiDataset(path, prefix)