code: def test_vertex_to_mni():
      """Test conversion of vertices to MNI coordinates."""
      pytest.importorskip("nibabel")
      # obtained using "tksurfer (sample) (l/r)h white"
      vertices = [100960, 7620, 150549, 96761]
      coords = np.array(
          [
              [-60.86, -11.18, -3.19],
              [-36.46, -93.18, -2.36],
              [-38.00, 50.08, -10.61],
              [47.14, 8.01, 46.93],
          ]
      )
      hemis = [0, 0, 0, 1]
      coords_2 = vertex_to_mni(vertices, hemis, "sample", subjects_dir)
      # less than 1mm error
      assert_allclose(coords, coords_2, atol=1.0)
  
file_path: mne-python/mne/tests/test_freesurfer.py
imports: from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  import mne
  from mne import get_volume_labels_from_aseg, head_to_mni, read_freesurfer_lut, read_talxfm, vertex_to_mni
  from mne._freesurfer import _check_subject_dir, _estimate_talxfm_rigid, _get_mgz_header, read_lta
  from mne.datasets import testing
  from mne.transforms import _angle_between_quats, _get_trans, apply_trans, rot_to_quat
label_desc: Use image node_id 3 for calling a global function with example usage: test_vertex_to_mni() without return types