class_docstr: EGL backend for Canvas abstract class.
code: def _vispy_swap_buffers(self):
      if self._surface is None:
          return
      # Swap front and back buffer
      egl.eglSwapBuffers(_EGL_DISPLAY, self._surface)
  
imports: from __future__ import division
  import atexit
  from time import sleep
  from ..base import BaseApplicationBackend, BaseCanvasBackend, BaseTimerBackend
  from ...util.ptime import time
  from ...None import config
label_desc: Use image node_id 6 for calling the CanvasBackend obj's underlying member method code with example usage: obj._vispy_swap_buffers() without return types