function strategy(closes, opens, highs, lows, volumes, price, symbol,
                  sma, ema, rsi, macd, bollinger, stochastic,
                  crossover, crossunder,
                  atr, sma_series, ema_series, rsi_series) {
  // Skalar: aktueller Wert
  const r = rsi(closes, 14);
  if (r === null) return NONE;
  if (r < 30) return LONG;
  if (r > 70) return SHORT;

  // Crossover immer mit Series-Funktionen:
  // if (crossover(ema_series(closes, 12), ema_series(closes, 26))) return LONG;

  return NONE;
}