code: function wrapIPv6Address (host, port) {
    if (!port) {
      if (host.indexOf('[') === 0) return host
      host = host.split(':')
      port = host[1]
      host = host[0]
    }
    return '[' + host + ']:' + port
  }
docs: support IPv6 https://www.ietf.org/rfc/rfc2732.txt