protected int indexOfStoredStrings(String s) {
        Integer index = storedStrings.get(s);
        if (debug) debug(
        	"indexOfStoredStrings(s=", StringUtil.toString(s), ") -> ",
        	String.valueOf((index != null ? index.intValue() : -1))
        );
        return (index != null ? index.intValue() : -1);
    }