// afterRequestに追加

//sannan.nl
if (url.match(/^https?:\/\/(?:sannan\.nl)\/(?<board>\w+)\/dat\/(?<key>\d+)\.dat$/)) {
  // DAT落ち
  if (404 == statusCode) {
    let base = new URL(url)
    let path = base.pathname
    let kako_url = new URL(path, 'https://kako.sannan.nl')
    // URLにkako.をつける
    let { headers, body } = await simplefetch(kako_url.href, {}, "GET")
    // 過去ログが作成されていたら
    if (headers['content-type'] == 'text/plain'){
      return { statusCode: 200, response_headers: headers, response_body: body }
    }
  }
  return { statusCode, response_headers, response_body }
}