Keltner Channel with Custom ATR

study(title="Keltner Channels with Custom ATR", shorttitle="KC ATR", overlay=true)
source = close
length = input(13, minval=1, title = "EMA Length")
atrlen = input(13, minval=1, title = "ATR Length")
mult = input(1.5)
ma = ema(source, length)
range =  tr
rangema = ema(range, atrlen)
upper = ma + rangema * mult
lower = ma - rangema * mult
c = gray
plot(upper, color=c, title="Upper")
plot(ma, color=c, title="Basis")
plot(lower, color=c, title="Lower")