4 接口的继承

interface Animal{
    name:string
    age:number
}
interface Dog extends Animal{
    eat(str:string):void;
}
class WolfDog implements Dog{
    name:string;
    age: number;
   eat(str:string):void{
       console.log(str);
   }
   constructor(name:string,age:number){
       this.name=name;
       this.age=age
   }
}
var w:WolfDog=new WolfDog('狗',8)