为什么struct Client（在coreos / etcd / clientv3 / client.go中）具有方法PUT [关闭]

The method PUT is in the interface KV, but the struct Client doesn't implement the the method in interface KV. So why it can use the method like this:

cli, err := clientv3.New(.....)
cli.Put(...)

As per godoc

type Client struct {
    Cluster
    KV
    Lease
    Watcher
    Auth
    Maintenance

    // Username is a user name for authentication.
    Username string
    // Password is a password for authentication.
    Password string
    // contains filtered or unexported fields
}

It means that a Client embeds a KV. So when calling Client.Put() the Put() method of KV is promoted and used instead.