// Note: First one will not be exact
static L<TradingCandle> convertToHeikinAshi(L<TradingCandle> candles) {
  L<TradingCandle> heikinAshi = emptyList(candles);
  TradingCandle prevHA = null;
  for i over candles: {
    var c = candles.get(i);
    TradingCandle ha = c.clone();
    ha.close((c.low()+c.high()+c.open()+c.close())/4);
    if (prevHA != null)
      ha.open((prevHA.open()+prevHA.close())/2);
    ha.low(min(ha.low(), ha.open()));
    ha.high(max(ha.high(), ha.open()));
    heikinAshi.add(ha);
    prevHA = ha;
  }
  ret heikinAshi;
}