@FunctionalInterface
    protected static interface ExecutorToken2BooleanFunction<T extends Token> {

        boolean apply(Executor exec, T token);
    }

    protected static class TokenFunctionMap {

        protected final Map<Class<? extends Token>, ExecutorToken2BooleanFunction<?>> internalMap = new HashMap<>();

        protected <T extends Token> void put(Class<T> clazz, ExecutorToken2BooleanFunction<T> function) {
            internalMap.put(clazz, function);
        }

        protected <T extends Token> ExecutorToken2BooleanFunction<T> get(Class<T> clazz) {
            return (ExecutorToken2BooleanFunction<T>) internalMap.get(clazz);
        }

        protected <T extends Token> boolean apply(Executor exec, T token) {
            return get((Class<T>) token.getClass()).apply(exec, token);
        }
    }