code: def _plot_topo_onpick(event, show_func):
      """Onpick callback that shows a single channel in a new figure."""
      # make sure that the swipe gesture in OS-X doesn't open many figures
      orig_ax = event.inaxes
      import matplotlib.pyplot as plt
  
      try:
          if hasattr(
              orig_ax, "_mne_axs"
          ):  # in unified, single-axes mode
              x, y = event.xdata, event.ydata
              for ax in orig_ax._mne_axs:
                  if (
                      x >= ax.pos[0]
                      and y >= ax.pos[1]
                      and x <= ax.pos[0] + ax.pos[2]
                      and y <= ax.pos[1] + ax.pos[3]
                  ):
                      orig_ax = ax
                      break
              else:
                  # no axis found
                  return
          elif not hasattr(orig_ax, "_mne_ch_idx"):
              # neither old nor new mode
              return
          ch_idx = orig_ax._mne_ch_idx
          face_color = orig_ax._mne_ax_face_color
          fig, ax = plt.subplots(1)
  
          plt.title(orig_ax._mne_ch_name)
          ax.set_facecolor(face_color)
  
          # allow custom function to override parameters
          show_func(ax, ch_idx)
          plt_show(fig=fig)
  
      except Exception as err:
          # matplotlib silently ignores exceptions in event handlers,
          # so we print
          # it here to know what went wrong
          print(err)
          raise
  
imports: from copy import deepcopy
  from functools import partial
  import numpy
  from scipy import ndimage
  from .._fiff.pick import channel_type, pick_types
  from ..defaults import _handle_default
  from ..utils import Bunch, _check_option, _clean_names, _is_numeric, _to_rgb, fill_doc
  from .utils import DraggableColorbar, _check_cov, _check_delayed_ssp, _draw_proj_checkbox, _plot_masked_image, _setup_ax_spines, _setup_vmin_vmax, add_background_image, plt_show
label_desc: Use image node_id 5 for calling a global function with example usage: _plot_topo_onpick(event, show_func) without return types