package main import (     "fmt" ) type Foo struct {     *Bar } type Bar struct {     Val int } func (b *Bar) Assign() {     b = &Bar{         Val: 20,     } } func main() {     myFoo := &Foo{}     myFoo.Bar.Assign()     fmt.Println(myFoo) }


??? 왜 실행 결과가 nil인것????