How to use the express-cassandra.doBatch function in express-cassandra

myinvestor.prototype.saveChosenStocks = function (stocks, callback) {
    // http://express-cassandra.readthedocs.io/en/latest/batch/
    var queries = [];
    for (var i = 0; i < stocks.length; i++) {
        var stock = stocks[i];
        var chosenStock = new models.instance.ChosenStock({
            category: stock.category,
            exchange_name: stock.exchange_name,
            stock_symbol: stock.stock_symbol
        }); 
        var saveQuery = chosenStock.save({ return_query: true });      
        queries.push(saveQuery);
    }

    models.doBatch(queries, function (err) {
        callback(err, stocks.length);
    });
}