Triple Bollinger Bands

study(title = "Triple Bollinger Bands", shorttitle="Triple BB", overlay=true)
source = close
length = input(20, minval=20, maxval=50)
stdDev1 = input(1.0, minval=1.0, maxval=1.3)
stdDev2 = input(2.0, minval=2.0, maxval=2.3)
stdDev3 = input(3.0, minval=3.0, maxval=3.3)

basis = sma(source, length)
dev1 = stdDev1 * stdev(source, length)
dev2 = stdDev2 * stdev(source, length)
dev3 = stdDev3 * stdev(source, length)

upper1 = basis + dev1
lower1 = basis - dev1
upper2 = basis + dev2
lower2 = basis - dev2
upper3 = basis + dev3
lower3 = basis - dev3

plot(basis, color=yellow)
p1 = plot(upper1, color=blue)
p2 = plot(lower1, color=blue)
p3 = plot(upper2, color=aqua)
p4 = plot(lower2, color=aqua)
p5 = plot(upper3, color=red)
p6 = plot(lower3, color=red)