code: def test_mpt_tokenizer_mask_user(self):
      tokenizer = get_nmt_tokenizer(
          library="huggingface",
          model_name="gpt2",
          merges_file=MERGE_FILE,
          vocab_file=VOCAB_FILE,
          use_fast=True,
      )
      tokenizer.add_special_tokens(
          {
              "additional_special_tokens": [
                  "<extra_id_0>",
                  "<extra_id_1>",
                  "<extra_id_2>",
              ]
          }
      )
      self._mask_user_test(tokenizer, partial(ids_to_text, tokenizer))
  
imports: import json
  import os
  import random
  from functools import partial
  import pytest
  from nemo.collections.nlp.data.language_modeling.megatron.gpt_sft_chat_dataset import GPTSFTChatDataset, get_prompt_template_example
  from nemo.collections.nlp.modules.common.tokenizer_utils import get_nmt_tokenizer
label_desc: Use image node_id 16 for calling the TestGPTSFTChatDataset obj's underlying member method code with example usage: obj.test_mpt_tokenizer_mask_user() without return types