code: def get_bert_tokenizer():
      """Bert (Wordpiece) tokenizer."""
      args = get_retro_args()
      lower_case = {
          "BertWordPieceLowerCase": True,
          "BertWordPieceCase": False,
      }[args.retro_bert_tokenizer_type]
      return _BertWordPieceTokenizer(
          vocab_file=args.retro_bert_vocab_file,
          lower_case=lower_case,
      )
  
file_path: megatron-lm/tools/retro/utils.py
imports: import os
  import torch
  import types
  from megatron import get_retro_args
  from megatron.tokenizer.tokenizer import _BertWordPieceTokenizer, _GPT2BPETokenizer, _GPTSentencePieceTokenizer
label_desc: Use image node_id 4 for calling a global function with example usage: get_bert_tokenizer() and returns: _BertWordPieceTokenizer