code: def _file_notifier(state):
      
      tstamp = time.time()
      state._tstamp = tstamp
      conf = state.app.config
  
      file_path = conf.get('WAFFLE_WATCHER_FILE', '/tmp/waffleconf.txt')
  
      if not os.path.isfile(file_path):
          # Create watch file
          open(file_path, 'a').close()
  
      # Update timestamp
      os.utime(file_path, (tstamp, tstamp))
docs: Notify of configuration update through file.
  
      Arguments:
          state (_WaffleState): Object that contains reference to app and its
              configstore.