code: def test_stockwell_ctf():
      """Test that Stockwell can be calculated on CTF data."""
      raw = read_raw_fif(raw_ctf_fname)
      raw.apply_gradient_compensation(3)
      events = make_fixed_length_events(raw, duration=0.5)
      evoked = Epochs(
          raw,
          events,
          tmin=-0.2,
          tmax=0.3,
          decim=10,
          preload=True,
          verbose="error",
      ).average()
      tfr_stockwell(evoked, verbose="error")
  
file_path: mne-python/mne/time_frequency/tests/test_stockwell.py
imports: from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_less, assert_equal
  from scipy import fftpack
  from mne import Epochs, make_fixed_length_events, read_events
  from mne.io import read_raw_fif
  from mne.time_frequency import AverageTFR, tfr_array_stockwell
  from mne.time_frequency._stockwell import _check_input_st, _precompute_st_windows, _st, _st_power_itc, tfr_stockwell
  from mne.utils import _record_warnings
label_desc: Use image node_id 1 for calling a global function with example usage: test_stockwell_ctf() without return types