Minecraft Turtle Auto build column v1.0

tArgs = {...}

local currentLevel = 0
local build = false
local currentSlot = 1
local length = 1
local width = 1

function isEmpty(slot)
  if turtle.getCount(slot) > 0 then
    return false
  else
    return true
  end
end

function nextSlot()
  currentSlot = currentSlot + 1
  turtle.select(currentSlot)
end

function buildColumn()
    while turtle.detectDown() == false do
        turtle.down()
        currentLevel = currentLevel + 1
      end

      if turtle.detectDown() == true then
        for i = 1, currentLevel do
          if isEmpty(currentSlot) == false
            turtle.up()
            turtle.placeDown()
          else
            nextSlot()
            i = i - 1
          end
        end
      end
end

if tArgs[1] == nil then
  print("Building a 1 x 1 column")
  build = true
else
  if tArgs[2] == nil then
    print("Invalid Usage.")
    print("Usage:")
    print("column")
    print("column length width")
    build = false
  else
    print("Building a "..tArgs[1].."x"..tArgs[2].." column")
    build = true
  end
end

if build == true then
  buildColumn()
  currentLevel = 0
  if length > 1 then
    for i = 1, length do
      if width > 1 then
        turtle.turnLeft()
        for i = 1, width do
          turtle.forward()
          buildColumn()
          currentLevel = 0
          for i = 1, width do
            turtle.back()
          end
        end
        turtle.turnRight()
      end
      turtle.forward()
      buildColumn()
      currentLevel = 0
    end
    for i = 1, length do
      turtle.back()
    end
  end
end