docstr: Destroy the given Toplevel, and if it was the last one,
  also destroy the Tk instance if we created it.
  
  Parameters
  ----------
  canvas : CanvasBackend
      The CanvasBackend to destroy, defaults to None.
code: def del_toplevel(cls, canvas=None):
      """
      Destroy the given Toplevel, and if it was the last one,
      also destroy the Tk instance if we created it.
  
      Parameters
      ----------
      canvas : CanvasBackend
          The CanvasBackend to destroy, defaults to None.
      """
      if canvas:
          try:
              canvas.destroy()
              if canvas.top:
                  canvas.top.destroy()
              cls._canvasses.remove(canvas)
          except Exception:
              pass
  
      # If there are no Toplevels left, quit the mainloop.
      if cls._tk_inst and not cls._canvasses and cls._tk_inst_owned:
          cls._tk_inst.quit()
          cls._tk_inst.destroy()
          cls._tk_inst = None
  
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 _TkInstanceManager obj's underlying member method code with example usage: obj.del_toplevel(cls, canvas) without return types