code: def test_equalize_channels():
      """Test equalization of channels for instances of Covariance."""
      cov1 = make_ad_hoc_cov(
          create_info(
              ["CH1", "CH2", "CH3", "CH4"], sfreq=1.0, ch_types="eeg"
          )
      )
      cov2 = make_ad_hoc_cov(
          create_info(["CH5", "CH1", "CH2"], sfreq=1.0, ch_types="eeg")
      )
      cov1, cov2 = equalize_channels([cov1, cov2])
      assert cov1.ch_names == ["CH1", "CH2"]
      assert cov2.ch_names == ["CH1", "CH2"]
  
imports: import itertools
  import sys
  from inspect import signature
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_equal, assert_equal
  from mne import Epochs, compute_covariance, compute_proj_raw, compute_rank, compute_raw_covariance, create_info, find_events, make_ad_hoc_cov, make_fixed_length_events, merge_events, pick_channels_cov, pick_info, pick_types, read_cov, read_evokeds, write_cov
  from mne._fiff.pick import _DATA_CH_TYPES_SPLIT
  from mne.channels import equalize_channels
  from mne.cov import _auto_low_rank_model, _regularized_covariance, compute_whitener, prepare_noise_cov, regularize, whiten_evoked
  from mne.datasets import testing
  from mne.fixes import _safe_svd
  from mne.io import RawArray, read_info, read_raw_ctf, read_raw_fif
  from mne.preprocessing import maxwell_filter
  from mne.rank import _compute_rank_int
  from mne.utils import _record_warnings, assert_snr, catch_logging
label_desc: Use image node_id 22 for calling a global function with example usage: test_equalize_channels() without return types