protected override Crossover?ComputeByIndexImpl(IEnumerable <decimal> mappedInputs, int index)
 => index >= 1 ? StateHelper.IsCrossover(_emaOsc[index], _emaOsc[index - 1]) : null;
 protected override Crossover?ComputeByIndexImpl(int index)
 => index >= 1 ? StateHelper.IsCrossover(_macd[index].MacdHistogram, _macd[index - 1].MacdHistogram) : null;
 protected override Crossover?ComputeByIndexImpl(int index)
 => index >= 1 ? StateHelper.IsCrossover(_smaOsc[index], _smaOsc[index - 1]) : null;
 protected override Crossover?ComputeByIndexImpl(IEnumerable <decimal> mappedInputs, int index)
 => index >= 1 ? StateHelper.IsCrossover(_macd[index].MacdHistogram, _macd[index - 1].MacdHistogram) : null;