@Override
 public ICommand removeCommand(Class<?> commandClazz) {
   ICommand command = (ICommand) interfaces.remove(commandClazz);
   if (command != null) command.enable(false);
   return command;
 }
 @Override
 public void addCommand(Class<?> clazz, ICommand instance) {
   interfaces.add(clazz, instance);
   instance.enable(true);
 }