docs: def beacon(config):
      '''
      Emit the status of a connected display to the minion
  
      Mainly this is used to detect when the display fails to connect
      for whatever reason.
  
      .. code-block:: yaml
  
          beacons:
            glxinfo:
              - user: frank
              - screen_event: True
  
      '''
  
      log.trace('glxinfo beacon starting')
      ret = []
  
      _config = {}
      list(map(_config.update, config))
  
      retcode = __salt__['cmd.retcode']('DISPLAY=:0 glxinfo',
                                        runas=_config['user'], python_shell=True)
  
      if 'screen_event' in _config and _config['screen_event']:
          last_value = last_state.get('screen_available', False)
          screen_available = retcode == 0
          if last_value != screen_available or 'screen_available' not in last_state:
              ret.append({'tag': 'screen_event', 'screen_available': screen_available})
  
          last_state['screen_available'] = screen_available
  
      return ret