code: def test_dpsswavelet():
      """Test DPSS tapers."""
      freqs = np.arange(5, 25, 3)
      Ws = _make_dpss(
          1000,
          freqs=freqs,
          n_cycles=freqs / 2.0,
          time_bandwidth=4.0,
          zero_mean=True,
      )
  
      assert len(Ws) == 3  # 3 tapers expected
  
      # Check that zero mean is true
      assert np.abs(np.mean(np.real(Ws[0][0]))) < 1e-5
  
      assert len(Ws[0]) == len(freqs)
  
imports: import datetime
  import re
  from itertools import product
  from pathlib import Path
  import matplotlib.pyplot
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal, assert_equal
  from scipy.signal import morlet2
  import mne
  from mne import Epochs, EpochsArray, Info, Transform, create_info, pick_types, read_events
  from mne.io import read_raw_fif
  from mne.tests.test_epochs import assert_metadata_equal
  from mne.time_frequency import tfr_array_morlet, tfr_array_multitaper
  from mne.time_frequency.tfr import AverageTFR, EpochsTFR, _compute_tfr, _make_dpss, combine_tfr, cwt, fwhm, morlet, read_tfrs, tfr_morlet, tfr_multitaper, write_tfrs
  from mne.utils import catch_logging, grand_average
  from mne.viz.utils import _fake_click, _fake_keypress, _fake_scroll
label_desc: Use image node_id 4 for calling a global function with example usage: test_dpsswavelet() without return types