code: def test_maxwell_filter_additional(tmp_path):
      """Test processing of Maxwell filtered data."""
      # TODO: Future tests integrate with mne/io/tests/test_proc_history
  
      # Load testing data (raw, SSS std origin, SSS non-standard origin)
      file_name = "test_move_anon"
      raw_fname = data_path / "SSS" / (file_name + "_raw.fif")
  
      # Use 2.0 seconds of data to get stable cov. estimate
      raw = read_crop(raw_fname, (0.0, 2.0))
  
      # Get MEG channels, compute Maxwell filtered data
      raw.load_data()
      raw.pick("meg")
      int_order = 8
      raw_sss = maxwell_filter(
          raw,
          origin=mf_head_origin,
          regularize=None,
          bad_condition="ignore",
      )
  
      # Test io on processed data
      test_outname = tmp_path / "test_raw_sss.fif"
      raw_sss.save(test_outname)
      raw_sss_loaded = read_crop(test_outname).load_data()
  
      # Some numerical imprecision since save uses 'single' fmt
      assert_allclose(
          raw_sss_loaded[:][0], raw_sss[:][0], rtol=1e-6, atol=1e-20
      )
  
      # Test rank of covariance matrices for raw and SSS processed data
      cov_raw = compute_raw_covariance(raw)
      cov_sss = compute_raw_covariance(raw_sss)
  
      scalings = None
      cov_raw_rank = _compute_rank_int(
          cov_raw, scalings=scalings, info=raw.info, proj=False
      )
      cov_sss_rank = _compute_rank_int(
          cov_sss, scalings=scalings, info=raw_sss.info, proj=False
      )
  
      assert cov_raw_rank == raw.info["nchan"]
      assert cov_sss_rank == _get_n_moments(int_order)
  
imports: import pathlib
  import re
  from contextlib import contextmanager
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  from scipy import sparse
  from scipy.special import sph_harm
  import mne
  from mne import compute_raw_covariance, concatenate_raws, pick_info, pick_types
  from mne._fiff.constants import FIFF
  from mne.annotations import _annotations_starts_stops
  from mne.chpi import filter_chpi, read_head_pos
  from mne.datasets import testing
  from mne.forward import _prep_meg_channels, use_coil_def
  from mne.io import BaseRaw, read_info, read_raw_bti, read_raw_ctf, read_raw_fif, read_raw_kit
  from mne.preprocessing import annotate_amplitude, annotate_movement, compute_maxwell_basis, find_bad_channels_maxwell, maxwell_filter, maxwell_filter_prepare_emptyroom
  from mne.preprocessing.maxwell import _bases_complex_to_real, _bases_real_to_complex, _get_n_moments, _prep_mf_coils, _sh_complex_to_real, _sh_negate, _sh_real_to_complex, _sss_basis_basic, _trans_sss_basis
  from mne.rank import _compute_rank_int, _get_rank_sss, compute_rank
  from mne.utils import _record_warnings, assert_meg_snr, buggy_mkl_svd, catch_logging, object_diff, use_log_level
label_desc: Use image node_id 9 for calling a global function with example usage: test_maxwell_filter_additional(tmp_path) without return types