sclass TradingCandle {
  // min, max, start and end prices
  settable double min;
  settable double max;
  settable double start;
  settable double end;
  
  settable Timestamp startTime;
  settable Timestamp endTime;
  settable bool ongoing;
  
  bool isGreen() {
    ret end > start;
  }
  
  bool isRed() {
    ret end < start;
  }
  
  bool isWhite() {
    ret end == start;
  }
  
  S colorText() {
    ret isGreen() ? "green"
      : isRed() ? "red"
      : "white";
  }
  
  void addValue(double price, Timestamp timestamp) {
    if (price < min) min = price;
    if (price > max) max = price;
    end = price;
    endTime = timestamp;
    if (startTime == null) {
      startTime = timestamp;
      start = price;
    }
  }
}