函数接收器调用未初始化的type类型，make初始化问题???

Question

我是新学者，下列代码会报错，原因是UserMap没有初始化，但是按照我下面的方法um = make(map[int]People)初始化，um在IDE里会出现灰色下划线警告，怎样做才能正确的初始化并使用，请指教，谢谢了

type People struct {
    Name string
    Sex  byte
}

type UserMap map[int]People

func (um UserMap) Get(id int) UserMap {
    //um = make(UserMap)
    um[id] = People{Name: "张三", Sex: 1}
    return um
}

func (um UserMap) Say(id int) UserMap {
    //um = make(map[int]People)
    delete(um, id)
    return um
}

func main() {
    var s UserMap
    val := s.Get(1)
    fmt.Println(val)
    val = s.Say(1)
    fmt.Println(val)
}

Answer 1

func main() {
    var s UserMap = make(UserMap)
    val := s.Get(1)
    fmt.Println(val)
    val = s.Say(1)
    fmt.Println(val)
}