code: def test_get_mni_fiducials():
      """Test get_mni_fiducials."""
      pytest.importorskip("nibabel")
      fids, coord_frame = read_fiducials(fid_fname)
      assert coord_frame == FIFF.FIFFV_COORD_MRI
      assert [f["ident"] for f in fids] == list(range(1, 4))
      fids = np.array([f["r"] for f in fids])
      fids_est = get_mni_fiducials("sample", subjects_dir)
      fids_est = np.array([f["r"] for f in fids_est])
      dists = np.linalg.norm(fids - fids_est, axis=-1) * 1000.0  # -> mm
      assert (dists < 8).all(), dists
  
imports: import os
  from functools import reduce
  from glob import glob
  from shutil import copyfile
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_equal, assert_array_less
  import mne
  from mne._fiff.constants import FIFF
  from mne.channels import DigMontage
  from mne.coreg import Coregistration, _is_mri_subject, coregister_fiducials, create_default_subject, fit_matched_points, get_mni_fiducials, scale_labels, scale_mri, scale_source_space
  from mne.datasets import testing
  from mne.io import read_fiducials, read_info
  from mne.source_space import write_source_spaces
  from mne.transforms import Transform, _angle_between_quats, apply_trans, invert_transform, read_trans, rot_to_quat, rotation, scaling, translation
  from mne.utils import catch_logging
label_desc: Use image node_id 6 for calling a global function with example usage: test_get_mni_fiducials() without return types