使用go语言根据微服务名称获取consul的微服务的时候，为什么是services啊？然后metainfo.LastIndex?

Question

var lastIndex uint64
    config := consulapi.DefaultConfig()
    config.Address = "127.0.0.1:8500"
    client, err := consulapi.NewClient(config)
    if err != nil {
        fmt.Println("api new client is failed, err:", err)
        return
    }
    services, metainfo, err := client.Health().Service("serverNode", "v1", true, &consulapi.QueryOptions{WaitIndex: lastIndex, // 同步点，这个调用将一直阻塞，直到有新的更新
    })
    if err != nil {
        log.Fatalf("error retrieving instances from Consul: %v", err)
    }
    lastIndex = metainfo.LastIndex
    addrs := map[string]struct{}{}
    for _, service := range services {
        fmt.Println("service.Service.Address:", service.Service.Address, "service.Service.Port:", service.Service.Port)
        addrs[net.JoinHostPort(service.Service.Address, strconv.Itoa(service.Service.Port))] = struct{}{}
    }