自定义方法后，如何插入新元素进行切片？ [重复]

When I tried to add a new method to an aliased type, append method not works.

package main

import (
  "fmt"
)
    type Strings []string

func (ss Strings) Add(s string) {
    ss = append(ss, s)
}

func main() {
    ss := make(Strings, 0)

    ss = append(ss, "haha", "h3h3")
    fmt.Println(ss) // got [haha h3h3]


    ss.Add("lala")
    fmt.Println(ss) // also got [haha h3h3], and why ?
}

Why doesn't "lala" get appended to ss?

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