public HttpRequest query(string parameter, string value = null) { var url = new UriBuilder(this.URL); var newQueryString = new FormUrlEncodedContent(new Dictionary <string, string> { { parameter, value } }).ReadAsStringAsync().Result; if (value == null) { newQueryString = newQueryString.Substring(0, newQueryString.Length - 1); } if (url.Query == "") { url.Query = newQueryString; } else { url.Query = string.Join("&", url.Query.Substring(1), newQueryString); } URL = url.Uri; return(this); }