code: def test_pick_channels():
      """Test if picking channels works with various arguments."""
      raw = read_raw_fif(raw_fname).crop(0, 0.1)
  
      # selected correctly 3 channels
      raw.pick(["MEG 0113", "MEG 0112", "MEG 0111"])
      assert len(raw.ch_names) == 3
  
      # selected correctly 3 channels and ignored 'meg', and emit warning
      with pytest.raises(ValueError, match="not present in the info"):
          raw.pick(["MEG 0113", "meg", "MEG 0112", "MEG 0111"])
  
      names_len = len(raw.ch_names)
      raw.pick(["all"])  # selected correctly all channels
      assert len(raw.ch_names) == names_len
      raw.pick("all")  # selected correctly all channels
      assert len(raw.ch_names) == names_len
  
imports: import hashlib
  from copy import deepcopy
  from functools import partial
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal, assert_equal
  from scipy.io import savemat
  from mne import Epochs, EpochsArray, EvokedArray, create_info, make_ad_hoc_cov, pick_channels, pick_types, read_events
  from mne._fiff.constants import FIFF, _ch_unit_mul_named
  from mne.channels import combine_channels, equalize_channels, find_ch_adjacency, get_builtin_ch_adjacencies, make_1020_channel_selections, read_ch_adjacency, read_custom_montage, rename_channels
  from mne.channels.channels import _BUILTIN_CHANNEL_ADJACENCIES, _BuiltinChannelAdjacency, _ch_neighbor_adjacency, _compute_ch_adjacency
  from mne.datasets import testing
  from mne.io import RawArray, read_info, read_raw_bti, read_raw_ctf, read_raw_eeglab, read_raw_fif, read_raw_kit
  from mne.parallel import parallel_func
  from mne.utils import requires_good_network
label_desc: Use image node_id 14 for calling a global function with example usage: test_pick_channels() without return types