let person: { name: string; age: number; sayHi(): void; greet(name: string) : void } = {
    name: 'Ken',
    age: 20,
    sayHi() {},
    greet(name) {}
}


let person2: {
    name: string
    age: number
    // sayHi: () => void
    // 也可是使用箭头函数
    sayHi: () => void
    greet(name: string): void
} = {
    name: 'Ken',
    age: 20,
    sayHi() {},
    greet(name) {}
}