nether

function place()
  if turtle.placeDown() == false then
    slot = slot + 1
    turtle.select(slot)
  end
end

slot = 1

for i=1,10 do
  d = 0
  while turtle.digDown() do
    d = d+1
    turtle.down()
  end
  turtle.up()
  for k=1, d do
    place()
  end
  turtle.forward()
  turtle.forward()
  turtle.forward()
end