code: def test_transforms(pdf, config, hs, exported):
      """Test transformations."""
      bti_trans = (0.0, 0.02, 0.11)
      bti_dev_t = Transform(
          "ctf_meg", "meg", _get_bti_dev_t(0.0, bti_trans)
      )
      raw = read_raw_bti(pdf, config, hs, preload=False)
      dev_ctf_t = raw.info["dev_ctf_t"]
      dev_head_t_old = raw.info["dev_head_t"]
      ctf_head_t = raw.info["ctf_head_t"]
  
      # 1) get BTI->Neuromag
      bti_dev_t = Transform(
          "ctf_meg", "meg", _get_bti_dev_t(0.0, bti_trans)
      )
  
      # 2) get Neuromag->BTI head
      t = combine_transforms(
          invert_transform(bti_dev_t), dev_ctf_t, "meg", "ctf_head"
      )
      # 3) get Neuromag->head
      dev_head_t_new = combine_transforms(t, ctf_head_t, "meg", "head")
  
      assert_array_equal(
          dev_head_t_new["trans"], dev_head_t_old["trans"]
      )
  
imports: import os
  from collections import Counter
  from functools import partial, reduce
  from io import BytesIO
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_equal, assert_equal
  import mne
  from mne import pick_info, pick_types
  from mne._fiff._digitization import _make_bti_dig_points
  from mne._fiff.constants import FIFF
  from mne.datasets import testing
  from mne.io import read_raw_bti, read_raw_fif
  from mne.io.bti.bti import _check_nan_dev_head_t, _convert_coil_trans, _correct_trans, _get_bti_dev_t, _get_bti_info, _loc_to_coil_trans, _read_bti_header, _read_config, _read_head_shape, _rename_channels
  from mne.io.tests.test_raw import _test_raw_reader
  from mne.transforms import Transform, combine_transforms, invert_transform
  from mne.utils import assert_dig_allclose
label_desc: Use image node_id 5 for calling a global function with example usage: test_transforms(pdf, config, hs, exported) without return types