通过指针获取值

How I can get a value by key through a pointer?

m := map[interface{}]interface{}{    
        "uid": "007",            
        "msg": "Hi James!",             
}                                  

fmt.Println(m["msg"]) //Ok!

p := &m

fmt.Println(p["msg"]) //??

play with: http://play.golang.org/p/4LOBrog93t

just through the value of the pointer:

fmt.Println((*p)["msg"])