static S doPost(Map urlParameters, S url) {
  ret doPost(makePostData(urlParameters), url);
}

static String doPost(S urlParameters, String url) ctex {
  URL _url = new URL(url);
  return doPost(urlParameters, _url.openConnection(), _url);
}

static String doPost(S urlParameters, URLConnection conn, URL url) ctex {
  setHeaders(conn);

  int l = lUtf8(urlParameters);
  print("Sending POST request: " + url + " (" + l + " bytes)");
      
  // connect and do POST
  conn.setDoOutput(true);
  conn.setRequestProperty("Content-Length", str(l));

  OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream(), "UTF-8");
  writer.write(urlParameters);
  writer.flush();

  String contents = loadPage(conn, url, false);
  writer.close();
  return contents;
}