class_docstr: A base class containing for the 2D browser.
  
  This class contains all backend-independent attributes and methods.
class_docstr_tok: ["A","base","class","containing","for","the","2D","browser",".","This","class","contains","all","backend-independent","attributes","and","methods","."]
docstr: Compute which channel indices to show.
docstr_tok: ["Compute","which","channel","indices","to","show","."]
code: def _update_picks(self):
      """Compute which channel indices to show."""
      if self.mne.butterfly and self.mne.ch_selections is not None:
          selections_dict = self._make_butterfly_selections_dict()
          self.mne.picks = np.concatenate(
              tuple(selections_dict.values())
          )
      elif self.mne.butterfly:
          self.mne.picks = self.mne.ch_order
      else:
          _slice = slice(
              self.mne.ch_start, self.mne.ch_start + self.mne.n_channels
          )
          self.mne.picks = self.mne.ch_order[_slice]
          self.mne.n_channels = len(self.mne.picks)
      assert isinstance(self.mne.picks, np.ndarray)
      assert self.mne.picks.dtype.kind == "i"
  
imports: import importlib
  from abc import ABC, abstractmethod
  from collections import OrderedDict
  from contextlib import contextmanager
  from copy import deepcopy
  from itertools import cycle
  import numpy
  from .._fiff.pick import _DATA_CH_TYPES_SPLIT
  from ..defaults import _handle_default
  from ..filter import _iir_filter, _overlap_add_filter
  from ..fixes import _compare_version
  from ..utils import _check_option, _get_stim_channel, _validate_type, get_config, logger, set_config, verbose
  from .backends._utils import VALID_BROWSE_BACKENDS
  from .utils import _get_color_list, _setup_plot_projector, _show_browser
label_desc: Use image node_id 9 for calling the BrowserBase obj's underlying member method code with example usage: obj._update_picks() without return types