Keltner Channels

study(title="Keltner Channels", shorttitle="KC", overlay=true)
useTrueRange = input(true)
length = input(20, minval=1)
mult = input(1.0)
src = input(close, title="Source")

ma = ema(src, length)
range = useTrueRange ? tr : high - low
rangema = ema(range, length)
upper = ma + rangema * mult
lower = ma - rangema * mult
c = blue
r = red
g = green
u = plot(upper, color=g, title="Upper")
plot(ma, color=c, title="Basis")
l = plot(lower, color=r, title="Lower")
fill(u, l, color=c)