static Map<S, S> slackGetChannelIDs(S token) {
  S url = "https://slack.com/api/channels.list";
  Map postData = litmap("token", token);
  S data = doPostWithTimeout(postData, url, slackSetTimeout_get());
  Map map = jsonDecodeMap(data);
  L<Map> channels = cast map.get("channels");
  new Map<S, S> out;
  for (Map c : channels) {
    S id = getString(c, "id");
    S name = getString(c, "name");
    out.put(name, id);
  }
  ret out;
}