code: def _mask_user_nolabel_test(self, tokenizer, ids_to_text):
      random.seed(5)
      temp_file = "/tmp/test_file.jsonl"
      turn_num = 5
      records = 5
      try:
          data_points = create_data_points(
              True, turn_num, records, temp_file, t2v=False, label=False
          )
          d = GPTSFTChatDataset(
              temp_file,
              tokenizer,
              4096,
              1,
              index_mapping_dir="/tmp/",
              hf_dataset=True,
              special_tokens=self.special_tokens,
          )
          for i in range(len(d)):
              result = d[i]
              input_ids = result["input_ids"]
              mask = result["mask"]
              text = ids_to_text(input_ids[mask].tolist())
              expected_text = ""
              for j in range(1, turn_num, 2):
                  expected_text += (
                      data_points[i]["conversations"][j]["value"]
                      + self.suffix
                  )
              assert text == expected_text
      finally:
          os.remove(temp_file)
  
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 6 for calling the TestGPTSFTChatDataset obj's underlying member method code with example usage: obj._mask_user_nolabel_test(tokenizer, ids_to_text) without return types