code: def test_evoked_filter():
      """Test filtering evoked data."""
      # this is mostly a smoke test as the Epochs and raw tests are more complete
      ave = read_evokeds(fname, 0).pick(picks="grad")
      ave.data[:] = 1.0
      assert round(ave.info["lowpass"]) == 172
      ave_filt = ave.copy().filter(None, 40.0, fir_design="firwin")
      assert ave_filt.info["lowpass"] == 40.0
      assert_allclose(ave.data, 1.0, atol=1e-6)
  
imports: import pickle
  from copy import deepcopy
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_equal, assert_equal
  from scipy import fftpack
  from mne import Epochs, EpochsArray, combine_evoked, create_info, equalize_channels, pick_types, read_events, read_evokeds, write_evokeds
  from mne._fiff.constants import FIFF
  from mne.evoked import Evoked, EvokedArray, _get_peak
  from mne.io import read_raw_fif
  from mne.utils import grand_average
label_desc: Use image node_id 12 for calling a global function with example usage: test_evoked_filter() without return types