public void addFunction(String name, List<String> arguments, String expression, boolean inline) {
        try {
            addFunction(parseRankingExpression(name, arguments, expression), inline);
        }
        catch (ParseException e) {
            throw new IllegalArgumentException("Invalid function '" + name + "'", e);
        }
    }
Whether we should ignore the default rank features. Set to null to use inherited
config-model/src/main/java/com/yahoo/schema/RankProfile.java