code: def _render_once(self):
      # See https://github.com/deepmind/dm_control/blob/92f9913013face0468442cd0964d5973ea2089ea/dm_control/viewer/gui/glfw_gui.py#L280  # noqa: E501
      window = self._window
      tick_func = self._tick_func
      if window._context and not glfw.window_should_close(
          window._context.window
      ):
          pixels = tick_func()
          with window._context.make_current() as ctx:
              ctx.call(
                  window._update_gui_on_render_thread,
                  window._context.window,
                  pixels,
              )
          window._mouse.process_events()
          window._keyboard.process_events()
      else:
          window.close()
  
imports: import dm_control.viewer.application
  import glfw
label_desc: Use image node_id 2 for calling the DmControlViewer obj's underlying member method code with example usage: obj._render_once() without return types