2x2 Tall Tree

local lSide = "right"
local height = 0
local red = redstone.getInput(lSide)

local function forward()
  while not turtle.forward() do
	  turtle.dig()
		turtle.attack()
		if turtle.getFuelLevel() < 1 then
		  error("Out of Fuel!")
		end
	end
end

local function plant()
  turtle.select(1)
	forward()
	forward()
	turtle.turnRight()
	turtle.place()
	turtle.turnLeft()
	turtle.back()
	turtle.place()
	turtle.turnRight()
	turtle.place()
	turtle.turnLeft()
	turtle.back()
	turtle.place()
	turtle.select(2)
	turtle.place()
end

local function up()
  turtle.dig()
	while not turtle.up() do
	  turtle.digUp()
  end
	turtle.dig()
end

local function new()
	forward()
	turtle.turnRight()
	forward()
	turtle.turnRight()
end

local function down()
  turtle.dig()
	while not turtle.down() do
	  turtle.dig()
		turtle.digDown()
	end
	turtle.dig()
end

local function reset()
  forward()
	forward()
	turtle.turnRight()
	forward()
	turtle.turnRight()
end

if red then
  plant()
	turtle.dig()
	forward()
	repeat
	  up()
		height = height + 1
  until not turtle.detectUp()
	new()
	repeat
	  down()
		height = height - 1
	until height == 0
  reset()
end