minecraft Pillar/wall digger turtle

args = {...}
height = args[1]
length = args[2]

function checkfuel()
	if turtle.getFuelLevel() <= 4 then
		turtle.select(16)
		turtle.refuel(1)
		turtle.select(1)
	end
end

function dig()
	while turtle.detect() do
		turtle.dig()
		os.sleep(.5)
	end
end

function digUp()
	while turtle.detectUp() do
		turtle.digUp()
		os.sleep(.5)
	end
end

function digDown()
	while turtle.detectDown() do
		turtle.digDown()
		os.sleep(.5)
	end
end

function forward()
	checkfuel()
	while turtle.forward() == false do
		dig()
		turtle.attack()
		checkfuel()
		os.sleep(.5)
	end
end

function up()
	checkfuel()
	while turtle.up() == false do
		digUp()
		turtle.attackUp()
		checkfuel()
		os.sleep(.5)
	end
end

function down()
	checkfuel()
	while turtle.down() == false do
		digDown()
		turtle.attackDown()
		checkfuel()
		os.sleep(.5)
	end
end

function pillar(hi,le)
	for i=1,le do
		forward()
		for o=1,hi-1 do
			if i % 2 == 1 then
				up()
			else
				down()
			end
		end
	end
	if le % 2 == 1 then
		for i=1,hi do
			down()
		end
	end
end

pillar(height,length)