code: def test_equalize_channels():
      """Test equalization of channels for instances of CrossSpectralDensity."""
      csd1 = _make_csd()
      # TODO replace with `.pick()` when CSD objects get that method
      csd2 = csd1.copy().pick_channels(["CH2", "CH1"], ordered=True)
      csd1, csd2 = equalize_channels([csd1, csd2])
  
      assert csd1.ch_names == ["CH1", "CH2"]
      assert csd2.ch_names == ["CH1", "CH2"]
  
imports: import pickle
  from itertools import product
  from os import path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  from pytest import raises
  import mne
  from mne.channels import equalize_channels
  from mne.proj import Projection
  from mne.time_frequency import CrossSpectralDensity, csd_array_fourier, csd_array_morlet, csd_array_multitaper, csd_fourier, csd_morlet, csd_multitaper, csd_tfr, pick_channels_csd, read_csd, tfr_morlet
  from mne.time_frequency.csd import _sym_mat_to_vector, _vector_to_sym_mat
  from mne.utils import sum_squared
label_desc: Use image node_id 18 for calling a global function with example usage: test_equalize_channels() without return types