code: func ConsentersToMap(consenters []*etcdraft.Consenter) map[string]struct{} {
  	set := map[string]struct{}{}
  	for _, c := range consenters {
  		set[string(c.ClientTlsCert)] = struct{}{}
  	}
  	return set
  }
docs: // ConsentersToMap maps consenters into set where key is client TLS certificate