code: def _find_child_at_position(self, group, position):
      children = [None]
      child = self._groups[group].get_first_child()
      while child is not None:
          children.append(child)
          child = child.get_next_sibling()
      return children[position]
  
imports: import functools
  import io
  import os
  import matplotlib
  from matplotlib import _api, backend_tools, cbook
  from matplotlib.backend_bases import ToolContainerBase, KeyEvent, LocationEvent, MouseEvent, ResizeEvent, CloseEvent
  from gi.repository import Gio, GLib, Gtk, Gdk, GdkPixbuf
  from .None import _backend_gtk
  from ._backend_gtk import _BackendGTK, _FigureCanvasGTK, _FigureManagerGTK, _NavigationToolbar2GTK, TimerGTK
label_desc: Use image node_id 3 for calling the ToolbarGTK4 obj's underlying member method code with example usage: obj._find_child_at_position(group, position) and returns: children