Computer Craft Turtle Wall Builder

local tArgs = {...}
local length = tArgs[1]
local height = tArgs[2]

local currentSlot = 1
local running = true

function fuel()
    if turtle.getFuelLevel() < 10 then
        turtle.select(16)
        turtle.refuel(1)
        turtle.select(currentSlot)
    end
end

function checkSlots()
    if turtle.getItemCount(turtle.getSelectedSlot()) < 1 then
        currentSlot = currentSlot + 1
        if currentSlot < 15 then
            turtle.select(currentSlot)
        else
            running = false
            print("HAVE RUN OUT  OF ITEMS")
        end
    end
end

function run()
    fuel()
    turtle.up()
    checkSlots()
    for y = 1, height do
        for x = 1, length do
            checkSlots()
            fuel()
            turtle.placeDown()
            if x < tonumber(length) then
                turtle.forward()
            end
        end
        fuel()
        turtle.turnLeft()
        turtle.turnLeft()
        turtle.up()
    end

end

run()