private String value;

    private String canonical;

    private ListItem items;

    private interface Item {
        int INT_ITEM = 3;
        int LONG_ITEM = 4;
        int BIGINTEGER_ITEM = 0;
        int STRING_ITEM = 1;
        int LIST_ITEM = 2;
        int COMBINATION_ITEM = 5;

        int compareTo(Item item);

        int getType();

        boolean isNull();
    }

    /**