Trying to understand why RSI has unstable period (according the docs), I explored that this period given not correct with "get_unstable_period" function
for name in [
            'ADX', 'ADXR', 'ATR', 'CMO', 'DX', 'EMA', 'HT_DCPERIOD',
            'HT_DCPHASE', 'HT_PHASOR', 'HT_SINE', 'HT_TRENDLINE',
            'HT_TRENDMODE', 'KAMA', 'MAMA', 'MFI', 'MINUS_DI', 'MINUS_DM',
            'NATR', 'PLUS_DI', 'PLUS_DM', 'RSI', 'STOCHRSI', 'T3', 'ALL'
        ]:
    print (name, talib.get_unstable_period(name))