private boolean loadWorld(CommandSender sender, String[] args) {
   if (args != null && args.length == 1) {
     WorldBase base = plugin.worldBases.get(args[0]);
     if (base != null) {
       WorldInstance instance = plugin.launchInstance(base, true);
       if (instance != null && sender instanceof Player) {
         Player player = (Player) sender;
         plugin.playerLocations.put(player.getName().toLowerCase(), instance.getWorldName());
         instance.teleport(player);
       }
     }
   }
   return true;
 }