golang map无法删除元素吗

make(map[KeyType]ValueType)

personSalary := make(map[string]int)

package main

import "fmt"

func main() {

    m := map[string]int{

        "a": 1,

        "b": 2,

        "c": 3,

    }

    fmt.Println("Deleting values")

    name, ok := m["a"]

    fmt.Println(name,ok)

    delete(m,"a")

    name,ok = m["a"]

    fmt.Println(name,ok)

}