REQUEST: A turtle script that removes water, lava, and oil from tunnels

local slot = 1
local length = 1

function instructions()
  term.clear()
  term.setCursorPos(1,1)
  print("Place turtle on the middle of the tunnel to be lava proofed. Tunnel should be 3 high, 1 wide and any length \(as long as there is an end.\)")
  io.read()
end

function checkInventory()
  repeat
	turtle.select(slot)
	if turtle.getItemCount() < 1 then
	  slot = slot + 1
	  if slot > 16 then
		slot = 1
	  end
	end
  until turtle.getItemCount() > 0
end

instructions()
checkInventory()
turtle.up()
while turtle.forward() do
  checkInventory()
  turtle.placeUp()
  turtle.turnLeft()
  checkInventory()
  turtle.place()
  turtle.turnRight()
  turtle.turnRight()
  checkInventory()
  turtle.place()
  turtle.turnLeft()
  length = length + 1
end
turtle.down()
for x = 1,(length-1) do
  turtle.turnLeft()
  checkInventory()
  turtle.place()
  turtle.turnRight()
  turtle.turnRight()
  checkInventory()
  turtle.place()
  turtle.turnLeft()
  turtle.back()
end
turtle.down()
for x = 1,length do
  checkInventory()
  turtle.placeDown()
  turtle.turnLeft()
  checkInventory()
  turtle.place()
  turtle.turnRight()
  turtle.turnRight()
  checkInventory()
  turtle.place()
  turtle.turnLeft()
  turtle.forward()
end
for x = 1,length do
  turtle.back()
end