docstr: Get or create the Tk instance.
  
  Returns
  -------
  tk.Tk
      The tk.Tk instance.
code: def _vispy_get_native_app(self):
      """Get or create the Tk instance.
  
      Returns
      -------
      tk.Tk
          The tk.Tk instance.
      """
      return _TkInstanceManager.get_tk_instance()
  
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 5 for calling the ApplicationBackend obj's underlying member method code with example usage: obj._vispy_get_native_app() and returns: _TkInstanceManager