sbtunnel.lua

function mineLayer()

    turtle.turnLeft()
    turtle.dig()
    turtle.turnRight()
    turtle.dig()
    turtle.turnRight()
    turtle.dig()
    turtle.turnLeft()

end


for i = 0,30,1
do
    turtle.select(1)

    -- check if we should refuel the turtle

    if turtle.getFuelLevel() < 10 then
        turtle.refuel(2)
    end

    -- mine
    turtle.digUp()
    mineLayer()
    turtle.up()
    mineLayer()

    -- check if we should place a torch below

    if i % 5 == 0 then
        turtle.select(4)
        turtle.placeDown()
        turtle.select(1)
    end

    --
    turtle.forward()
    mineLayer()
    turtle.down()
    mineLayer()
    turtle.forward()

end