从某个类型中挑出一些属性出来

    1. type Person = {
    2.   name: string;
    3.   age:number;
    4.   gender:string
    5. }
    7. type P1 = Pick<Person, "name" | "age">; // { name: string; age: number; }
    9. const user:P1={
    10.   name:'树哥',
    11.   age:18
    12. }