def METHOD_NAME(opts, parser, extra_arg_groups=None):
    from rez.config import config
    from rez.packages import iter_package_families, iter_packages
    from rez.utils.yaml import dump_yaml
    from rez.utils.memcached import Client
    from rez.utils.formatting import columnise, readable_time_duration, \
        readable_memory_size
    import sys
    memcache_client = Client(servers=config.memcached_uri,
                             debug=config.debug_memcache)
    if not memcache_client:
        print("memcaching is not enabled.", file=sys.stderr)
        sys.exit(1)
    if opts.poll:
        poll(memcache_client, opts.interval)
        return
    if opts.flush:
        memcache_client.flush(hard=True)
        print("memcached servers are flushed.")
        return
    if opts.warm:
        seen = set()
        paths = config.nonlocal_packages_path
        for family in iter_package_families(paths=paths):
            if family.name in seen:
                continue
            for package in iter_packages(family.name, paths=paths):
                if opts.verbose:
                    print("warming: %s" % package.qualified_name)
                # forces package definition load, which puts in memcache
                _ = package.data  # noqa
            seen.add(family.name)
        print("memcached servers are warmed.")
        return
    if opts.reset_stats:
        memcache_client.reset_stats()
        print("memcached servers are stat reset.")
        return
    def _fail():
        print("memcached servers are not responding.", file=sys.stderr)
        sys.exit(1)
    stats = memcache_client.get_stats()
    if opts.stats:
        if stats:
            txt = dump_yaml(stats)
            print(txt)
        else:
            _fail()
        return
    # print stats summary
    if not stats:
        _fail()
    rows = [["CACHE SERVER", "UPTIME", "HITS", "MISSES", "HIT RATIO", "MEMORY", "USED"],
            ["------------", "------", "----", "------", "---------", "------", "----"]]
    for server_id, stats_dict in stats:
        server_uri = server_id.split()[0]
        uptime = int(stats_dict.get("uptime", 0))
        hits = int(stats_dict.get("get_hits", 0))
        misses = int(stats_dict.get("get_misses", 0))
        memory = int(stats_dict.get("limit_maxbytes", 0))
        used = int(stats_dict.get("bytes", 0))
        hit_ratio = float(hits) / max(hits + misses, 1)
        hit_percent = int(hit_ratio * 100.0)
        used_ratio = float(used) / max(memory, 1)
        used_percent = int(used_ratio * 100.0)
        row = (server_uri,
               readable_time_duration(uptime),
               str(hits),
               str(misses),
               "%d%%" % hit_percent,
               readable_memory_size(memory),
               "%s (%d%%)" % (readable_memory_size(used), used_percent))
        rows.append(row)
    print('\n'.join(columnise(rows)))