private String formatHelpTitle() {
        if (isOptionalArgument()) {
            String mv = formatMetavar();
            StringBuilder sb = new StringBuilder();

            if(ArgumentParsers.isSingleMetavar()) {
                for (String flag : flags_) {
                    if(sb.length() > 0) {
                        sb.append(", ");
                    }
                    sb.append(flag);
                }
                if (!mv.isEmpty()) {
                    sb.append(" ").append(mv);
                }
            } else {
                for (String flag : flags_) {
                    sb.append(flag);
                    if (!mv.isEmpty()) {
                        sb.append(" ").append(mv);
                    }
                    sb.append(", ");
                }
                if (sb.length() > 2) {
                    sb.delete(sb.length() - 2, sb.length());
                }
            }
            return sb.toString();
        } else {
            return resolveMetavar()[0];
        }
    }