fun onEntryMessage(msg: Message) {
  val newbie = msg.sender
  group.restrictWriting(newbie)
  timer.scheduleFor(newbie, cfg.kickoutDelay) { group.kick(newbie) }
  val (problem, decisions, truth) = randomProblem()
  msg.replyWith(Photo(problem)
    .withBoard(createRows(decisions)) {
    if (it.index == truth) onEntryApproved(msg)
    else onEntryFailed(msg)
  })
  //nothing
}
fun onEntryApproved(msg: Message) {
  timer.cancalFor(msg.sender)
  //congratulations
}
fun onEntryFailed(msg: Message) {
  //so bad
}
fun Group.restrictWriting(user: User) = TODO()
//……N abstraction = TODO

const filter = browser.webRequest.filterResponseData(e.requestId);
let buffers = null; //result

// onNext, onDone, onError
filter.ondata = (event) => {
  const data = event.data;
  if (buffers === null) {
    buffers = new Uint8Array(data); return;
  }
  const buffer = new Uint8Array(buffers.byteLength + data.byteLength);
  //v 将响应分段数据收集拼接起来，在完成加载后整体替换。这可能会改变浏览器接收数据分段渲染的行为。
  buffer.set(buffers); buffer.set(new Uint8Array(data), buffers.buffer.byteLength);
  buffers = buffer;
}

filter.onstop = () => {
  if (buffers === null) { filter.close(); return; }

  for (let item of rule) { //< 缓存实例，减少开销
    const encoding = item.encoding || "UTF-8";
    try {
      const _text = this._textDecode(encoding, buffers.buffer);
      const text = item._func(_text, detail);
      if (typeof text === 'string' && text !== _text) { buffers = this._textEncode(encoding, text); }
    } catch (e) { console.error(e); }
  }

  filter.write(buffers.buffer);
  buffers = null;
  filter.close();
}

filter.onerror = () => { buffers = null; }