class_docstr: Dataset for bert pretraining when using data preprocessing including tokenization
class_docstr_tok: ["Dataset","for","bert","pretraining","when","using","data","preprocessing","including","tokenization"]
code: def __len__(self):
      return self.corpus_size
  
imports: import array
  import os
  import pickle
  import random
  from typing import Dict, List, Optional
  import h5py
  import numpy
  from torch.utils.data import DataLoader, DistributedSampler
  from tqdm import tqdm
  from nemo.collections.nlp.data.data_utils.data_preprocessing import find_newlines, load_data_indices
  from nemo.core.classes import Dataset
label_desc: Use image node_id 2 for calling the BertPretrainingDataset obj's underlying member method code with example usage: obj.__len__() and returns: self