code: public int asHttpCode() throws HelloSignException {
          Integer code = getLastResponseCode();
          if (code == null) {
              throw new HelloSignException("No request performed");
          }
          if (code >= 200 && code < 300) {
              reset();
              return code;
          }
          throw new HelloSignException("HTTP Code " + code, code);
      }
docs: Executes the request and returns the HTTP response code.
  
  @return int HTTP response code
  @throws HelloSignException thrown if no request has been performed