code: def test_pick_types_csd():
      """Test pick_types(csd=True)."""
      # info with laplacian/CSD channels at indices 1, 2
      names = ["F1", "F2", "C1", "C2", "A1", "A2", "misc1", "CSD1"]
      info1 = create_info(
          names,
          256,
          ["eeg", "eeg", "eeg", "eeg", "mag", "mag", "misc", "csd"],
      )
      raw = RawArray(np.zeros((8, 512)), info1)
      raw.set_montage(
          make_standard_montage("standard_1020"), verbose="error"
      )
      raw_csd = compute_current_source_density(raw, verbose="error")
  
      assert_array_equal(pick_types(info1, csd=True), [7])
  
      # pick from the raw object
      assert raw_csd.copy().pick("csd").ch_names == [
          "F1",
          "F2",
          "C1",
          "C2",
          "CSD1",
      ]
  
imports: from copy import deepcopy
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from mne import Epochs, channel_indices_by_type, channel_type, create_info, make_ad_hoc_cov, pick_channels, pick_channels_cov, pick_channels_regexp, pick_info, pick_types, pick_types_forward, read_forward_solution, rename_channels
  from mne._fiff.constants import FIFF
  from mne._fiff.pick import _DATA_CH_TYPES_SPLIT, _contains_ch_type, _picks_by_type, _picks_to_idx, get_channel_type_constants
  from mne.channels import make_standard_montage
  from mne.datasets import testing
  from mne.io import RawArray, read_info, read_raw_bti, read_raw_fif, read_raw_kit
  from mne.preprocessing import compute_current_source_density
  from mne.utils import assert_object_equal, catch_logging
label_desc: Use image node_id 21 for calling a global function with example usage: test_pick_types_csd() without return types