sclass TradingSignal {
  settable S coin;
  settable bool isLong;
  settable Timestamp timestamp;
  settable TradingRun afterRun;
  
  toString {
    S text = (isLong ? "Long" : "Short") + " signal at "
      + timestamp;
    if (afterRun != null)
      text += " after " + formatDouble2X(afterRun.changePercent()) + "% run";
    ret text;
  }
}