code: def test_jsonl_mem_map_dataset(jsonl_file):
      """Test for JSONL memory-mapped datasets."""
  
      indexed_dataset = text_memmap_dataset.JSONLMemMapDataset(
          dataset_paths=[jsonl_file], header_lines=0
      )
      assert indexed_dataset[0] == {"name": "John", "age": 30}
      assert indexed_dataset[1] == {"name": "Jane", "age": 25}
      assert indexed_dataset[2] == {"name": "Bob", "age": 35}
  
file_path: NeMo/tests/collections/nlp/test_mem_map_dataset.py
imports: import csv
  import json
  import os
  import pytest
  from nemo.collections.nlp.data.language_modeling import text_memmap_dataset
label_desc: Use image node_id 3 for calling a global function with example usage: test_jsonl_mem_map_dataset(jsonl_file) without return types