code: def pick_channels_csd(
      csd,
      include=[],
      exclude=[],
      ordered=None,
      copy=True,
      *,
      verbose=None,
  ):
      """Pick channels from cross-spectral density matrix.
  
      Parameters
      ----------
      csd : instance of CrossSpectralDensity
          The CSD object to select the channels from.
      include : list of str
          List of channels to include (if empty, include all available).
      exclude : list of str
          Channels to exclude (if empty, do not exclude any).
      %(ordered)s
      copy : bool
          If True (the default), return a copy of the CSD matrix with the
          modified channels. If False, channels are modified in-place.
  
          .. versionadded:: 0.20.0
      %(verbose)s
  
      Returns
      -------
      res : instance of CrossSpectralDensity
          Cross-spectral density restricted to selected channels.
      """
      if copy:
          csd = csd.copy()
  
      sel = pick_channels(
          csd.ch_names,
          include=include,
          exclude=exclude,
          ordered=ordered,
      )
      data = []
      for vec in csd._data.T:
          mat = _vector_to_sym_mat(vec)
          mat = mat[sel, :][:, sel]
          data.append(_sym_mat_to_vector(mat))
      ch_names = [csd.ch_names[i] for i in sel]
  
      csd._data = np.array(data).T
      csd.ch_names = ch_names
      return csd
  
imports: import copy
  import numbers
  import numpy
  from scipy.fft import rfftfreq
  from .._fiff.pick import _picks_to_idx, pick_channels
  from ..parallel import parallel_func
  from ..time_frequency.multitaper import _compute_mt_params, _csd_from_mt, _mt_spectra, _psd_from_mt_adaptive
  from ..utils import ProgressBar, _check_fname, _import_h5io_funcs, _validate_type, copy_function_doc_to_method_doc, logger, verbose, warn
  from ..viz.misc import plot_csd
  from .tfr import EpochsTFR, _cwt_array, _get_nfft, morlet
label_desc: Use image node_id 1 for calling a global function with example usage: pick_channels_csd(csd, include, exclude, ordered, copy) and returns: csd