[RS]Dynamic Range Commodity Channel Index V0

study(title="[RS]Dynamic Range Commodity Channel Index V0", shorttitle="DR-CCI", overlay=false)
length = input(title='CCI Length:', type=integer, defval=20)
smooth = input(title='CCI Smoothing:', type=integer, defval=1)
f_cci(_src, _length) =>
    _ma = sma(_src, _length)
    _return = (_src - _ma) / (0.015 * dev(_src, _length))

c = ema(ema(f_cci(close-close[1], length), smooth), smooth)
pos = stdev(c, length)
neg = -stdev(c, length)

h = highest(max(pos, neg), length)
l = lowest(min(pos, neg), length)

ob = plot(title='OB', series=h, color=lime)
os = plot(title='OS', series=l, color=red)
fill(ob, os, color=silver, transp=50)

plot(title='CCI', series=c, color=black)