docstr: Class-specific build method to be overridden by child classes.
docstr_tok: ["Class-specific","build","method","to","be","overridden","by","child","classes","."]
code: def _build(self):
      """
      Class-specific build method to be overridden by child classes.
      """
      self.sentinel_tokens = (
          self.tokenizer.additional_special_tokens_ids
      )
      assert len(self.sentinel_tokens) > 0
  
imports: import collections
  import os
  import numpy
  import torch
  from nemo.collections.common.tokenizers import SentencePieceTokenizer, YouTokenToMeTokenizer
  from nemo.collections.nlp.data.language_modeling.megatron.dataset_utils import create_masked_lm_predictions, get_samples_mapping
  from nemo.collections.nlp.data.language_modeling.megatron.gpt_dataset import _build_index_mappings
  from nemo.core import Dataset
label_desc: Use image node_id 2 for calling the T5Dataset obj's underlying member method code with example usage: obj._build() without return types