persistable sclass TickerSequence is IntSize {
  new LongBuffer timestamps;
  new DoubleBuffer prices;
  
  void add(double price, long timestamp) {
    timestamps.add(timestamp);
    prices.add(price);
  }
  
  void add(double[] prices, long[] timestamps) {
    assertEquals(l(prices), l(timestamps));
    this.prices.addAll(asList(prices));
    this.timestamps.addAll(asList(timestamps));
  }
  
  toString {
    ret "TickerSequence length " + n2(l(prices));
  }
  
  TickerSequence subSequence(int start, int end) {
    new TickerSequence s;
    s.add(
      subDoubleArray(prices.toArray(), start, end),
      subArray(timestamps.toArray(), start, end));
    ret s;
  }
  
  public int size() { ret l(prices); }
}