private static String parseParam(String s, String prefix) {
        if (s.startsWith(prefix) && s.length() > prefix.length()) {
            return s.substring(prefix.length());
        }
        return null;
    }
Contains the standard {@link MetaStackElement}s provided by LuckPerms.
common/src/main/java/me/lucko/luckperms/common/cacheddata/metastack/StandardStackElements.java