for example, 

BollingerBands bb;
        RelativeStrengthIndex rsi;
        AverageTrueRange atr;
        ExponentialMovingAverage ema;
        SimpleMovingAverage sma;
        MovingAverageConvergenceDivergence macd;
        AroonOscillator aroon;
        Momentum mom;
        StandardDeviation std;

How do I know, bb has a method : lowerBand()?

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