@EventHandler
    public void onSignChange(SignChangeEvent event) {
        World world = event.getBlock().getWorld();
        int x = event.getBlock().getX();
        int y = event.getBlock().getY();
        int z = event.getBlock().getZ();
        String string = stringBuilder.BuildString(world, x, y, z) + "_exists";
        Player player = event.getPlayer();
        if (event.getLine(0).equals("[Class]")) {
            if (player.hasPermission("classign.user.place")) {
                if (props.classes.contains(event.getLine(1))) {
                    event.setLine(3, ChatColor.GREEN + "[Active]");
                    plugin.signSet.put(string, true);
                }
            }
        }
    }