code: def test_fetch_icbm152_brain_gm_mask(tmp_path):
      dataset = struct.fetch_icbm152_2009(
          data_dir=str(tmp_path), verbose=0
      )
      struct.load_mni152_template(resolution=2).to_filename(dataset.gm)
      grey_matter_img = struct.fetch_icbm152_brain_gm_mask(
          data_dir=str(tmp_path), verbose=0
      )
  
      assert isinstance(grey_matter_img, Nifti1Image)
  
file_path: nilearn/nilearn/datasets/tests/test_struct.py
imports: from pathlib import Path
  import numpy
  import pandas
  import pytest
  from nibabel import Nifti1Image
  from nilearn.datasets import struct
  from nilearn.datasets.tests._testing import dict_to_archive, list_to_archive
label_desc: Use image node_id 5 for calling a global function with example usage: test_fetch_icbm152_brain_gm_mask(tmp_path) without return types