OpenRadio turtle

modem = peripheral.wrap("left")
modem.open(123)
local radio = {}
local current = 0
local volume = 0

turtle.select(1)
turtle.suck()

function switch(nb)
    turtle.select(1)
    turtle.suck()
    if nb ~= 0 then
        turtle.select(nb)
        turtle.drop()
        turtle.select(1)
    end
end

while true do
    local event, side, sender, reply, message = os.pullEvent("modem_message")
    if sender == 123 then
        radio = textutils.unserialize(message)
        print(radio["fr"] ..":".. radio["vl"])
        if radio["fr"] ~= current then
            switch(radio["fr"])
            current = radio["fr"]
        end
        if radio["vl"] ~= volume then
            rs.setAnalogOutput("front",radio["vl"])
        end
    end
    sleep(2)
end