Make Air Shaft (maybe smarter)

-- Will create an air shaft to the surface

function checkfuel()
  if turtle.getFuelLevel() == 0 then
    print "Out of Fuel"
    exit()
  end
end

function findCeiling()
  while not turtle.detectUp() do
    turtle.up()
    checkfuel()
    sleep(0)
  end
end

function digShaft()
  while turtle.detectUp() do
    if turtle.digUp() then turtle.up() end
    checkfuel()
    sleep(0)
  end
end

function park()
  local turns = 0
  while turtle.detect() do
    turtle.turnLeft()
    turns = turns + 1
    if turns % 4 == 0 then
      if turtle.detectUp() then turtle.digUp() end
      turtle.up()
      checkfuel()
    end
    sleep(0)
  end
  turtle.forward()
end

findCeiling()
digShaft()
park()