docstr: Destroy each created Toplevel by calling _vispy_close on it.
  If there are no Toplevels left, also destroy the Tk instance.
code: def _vispy_quit(self):
      """Destroy each created Toplevel by calling _vispy_close on it.
      If there are no Toplevels left, also destroy the Tk instance.
      """
      for c in _TkInstanceManager.get_canvasses():
          c._vispy_close()
      _TkInstanceManager.del_toplevel()
  
imports: from __future__ import division
  from time import sleep
  import warnings
  from ..base import BaseApplicationBackend, BaseCanvasBackend, BaseTimerBackend
  from ...util import keys
  from ...util.ptime import time
  from ...gloo import gl
label_desc: Use image node_id 4 for calling the ApplicationBackend obj's underlying member method code with example usage: obj._vispy_quit() without return types