package mainimport "fmt"type Subject interface {   Do() string}type RelSubject struct {}func (r *RelSubject) Do() string {   return "test"}type Proxy struct {   real RelSubject}func (proxy *Proxy) Do() string {  res := proxy.real.Do()  return res}func main() {   var sub Subject   sub = &Proxy{}   res := sub.Do()   fmt.Println(res)}复制代码