function dig(up, down)
    while turtle.detect() do
        turtle.dig()
    end
    if up or down then
        turtle.forward()
    end
    if up then
        turtle.digUp()
    end
    if down then
        turtle.digDown()
    end
end

dig(true, false)
turtle.up()
dig(true, true)
turtle.turnLeft()
for i=1,4 do
    dig(true, true)
end
turtle.turnRight()
for j=1,4 do
    for i=1,8 do
        dig(true, true)
    end
    turtle.turnRight()
    dig(true, true)
    turtle.turnRight()
    for i=1,8 do
        dig(true, true)
    end
    turtle.turnLeft()
    dig(true, true)
    turtle.turnLeft()
end
for i=1,8 do
    dig(true, true)
end
turtle.down()
turtle.turnLeft()
for i=1,4 do
    turtle.forward()
end
turtle.turnLeft()
for i=1,4 do
    turtle.forward()
end