code: func (s *Serf) DefaultQueryTimeout() time.Duration {
  	n := s.memberlist.NumMembers()
  	timeout := s.config.MemberlistConfig.GossipInterval
  	timeout *= time.Duration(s.config.QueryTimeoutMult)
  	timeout *= time.Duration(math.Ceil(math.Log10(float64(n + 1))))
  	return timeout
  }
docs: // DefaultQueryTimeout returns the default timeout value for a query
  // Computed as GossipInterval * QueryTimeoutMult * log(N+1)