Minecraft Turtle: Bridge

slot = 1

function getSlot()
    while turtle.getItemCount(slot) == 0 and slot < 16 do
        slot = slot + 1
    end
    if turtle.getItemCount(slot) == 0 and slot == 16 then
        print("No more ressources... Fill me up and press enter")
        read()
        slot = 1
    end
end

local args = { ... }
if #args < 1 then
    print("")
    print("Usage: bridge <length> <buildSides 0|1>")
    print("")

    error()
end

if #args >= 1 then
    length = tonumber(args[1])
    sides = 0
end

if #args >= 2 then
    length = tonumber(args[1])
    sides = tonumber(args[2])
end

if turtle.getFuelLevel() < length then
    print("I need " .. length - turtle.getFuelLevel() .. " more fuel!")
else
    print("======== 2019 (c) psychedelixx ========")
    print("Let's go!")

        while length > 0 do
            print("Remaining: " .. length)

            t.dig()
            t.forward()

            t.placeDown(slot)
            getSlot()

            if sides == 1 then
              t.placeLeft(slot)
              getSlot()
              t.placeRight(slot)
              getSlot()
            end

            length = length - 1
        end

        t.place(slot)
end