function select_next_item()
    local sel_pos = 0
    turtle.select(sel_pos + 1)

    while(turtle.getItemCount() <= 0) do
        sel_pos = (sel_pos + 1) % 16
        turtle.select(sel_pos + 1)
    end
end

while(true) do
    select_next_item()
    for i = 1,4,1 do
        turtle.place()
        turtle.turnRight()
    end
    sleep(20)
end