CC Turtle Wide Tunnel

args={...}
d=tonumber(args[1])

function dumpExcess()
    if turtle.getItemCount(16)>0 then
        turtle.select(1)
        turtle.placeDown()
            for is=2,16 do
                turtle.select(is)
                turtle.dropDown()
            end
        turtle.select(1)
    end
end

function safeDig()
        while turtle.detectUp() end
            turtle.digUp()
        end
    turtle.digDown()
    turtle.dig()
    dumpExcess()
end

turtle.dig()
turtle.forward()
turtle.turnRight()

while true do
    for i=1,d do
        safeDig()
    end
turtle.turnLeft()
safeDig()
turtle.forward()
safeDig()
turtle.turnLeft()
    for i=1,d do
        safeDig()
    end
turtle.turnRight()
safeDig()
turtle.forward()
safeDig()
turtle.turnRight()
end