code: public FutureData<Balance> balance() {
          FutureData<Balance> future = new FutureData<Balance>();
          URI uri = newParams().forURL(config.newAPIEndpointURI(BALANCE));
          Request request = config.http().GET(uri, new PageReader(newRequestCallback(future, new Balance(), config)));
          performRequest(future, request);
          return future;
      }
docs: /*
  @return The balance on the account being used to make API calls