public void addSymbol(String symbol) {
   Stock stock = Stock.find("bySymbol", symbol).one();
   if (stock == null) {
     stock = new Stock(symbol);
     stock.save();
   }
 }
 public StockPrice[] getStocks() {
   List<Stock> stocks = Stock.findAll();
   StockPrice[] prices = new StockPrice[stocks.size()];
   for (int i = 0; i < stocks.size(); i++) {
     prices[i] = stocks.get(i).asStockPrice();
   }
   return prices;
 }
 public void removeSymbol(String symbol) {
   Stock stock = Stock.find("bySymbol", symbol).one();
   if (stock != null) {
     stock.delete();
   }
 }