code: def test_compare_fiff():
      """Test compare_fiff."""
      compare_fiff(raw_fname, cov_fname, read_limit=0, show=False)
      plt.close("all")
  
imports: from pathlib import Path
  import matplotlib.pyplot
  import numpy
  import pytest
  from numpy.testing import assert_allclose
  from mne import read_evokeds
  from mne.epochs import Epochs
  from mne.event import read_events
  from mne.io import read_raw_fif
  from mne.viz import ClickableImage, add_background_image, mne_analyze_colormap
  from mne.viz.ui_events import ColormapRange, link, subscribe
  from mne.viz.utils import _compute_scalings, _fake_click, _fake_keypress, _fake_scroll, _get_color_list, _make_event_color_dict, _setup_vmin_vmax, _validate_if_list_of_axes, centers_to_edges, compare_fiff, concatenate_images
label_desc: Use image node_id 4 for calling a global function with example usage: test_compare_fiff() without return types