Plus-shaped tunnel

--put torches in slot 16 and enjoy
function df()
    while turtle.detect() do
        turtle.dig()
        sleep(0.5)
    end
end

--mine the first block
df()
counter = 0

while (not turtle.detect()) and counter <= 66 do
    if turtle.forward() then
        df()
        while turtle.detectUp() do
            turtle.digUp()
            sleep(0.5)
        end

        if turtle.detectDown() then
            turtle.digDown()
        end

        if (turtle.getItemCount(16) > 1) then
            if ((counter % 11) == 0) then
                turtle.select(16)
                turtle.placeDown()
            end
        end

        turtle.turnLeft()
        df()

        turtle.turnLeft()
        turtle.turnLeft()
        df()

        turtle.turnLeft()
        counter = counter + 1
    else
        sleep(1)
    end
end