不允许子类重写指定方法

class Father {  
    name!: string;  
    constructor() {  
        this.say()  
    }  
    private say() {  
        console.log('father')  
    }  
}  
class Son extends Father {  
    constructor() {  
        super()  
        this.say()  
    }  
    /* 不允许重写private方法 */  
    say() {  
        console.log('son')  
    }  
}  
let son = new Son()