sclass PostRequest {
  S method = "POST";
  S url;
  MapSO params = new LinkedHashMap;
  SS headers = new LinkedHashMap;
  
  *() {}
  *(S *url, O... _) { params = paramsToMap(_); }
  
  S perform() {
    if (eq(method, "POST"))
      ret doPostWithHeaders(url, headers, params);
    else if (eq(method, "GET"))
      ret loadPageWithHeaders(appendQueryToURL(url, params), headers);
    else fail("Unknown method: " + method);
  }
  
  selfType set(S param, O value) {
    params.put(param, value);
    this;
  }
  
  selfType switchToGet() {
    method = "GET";
    this;
  }
}