類似下面這種代碼get(obj,'k1','k2','k3')     .then((v)=>console.log(v))     .else(()=>console.log('值為空'));實(shí)現(xiàn)下面這種代碼的功能if(obj && obj.k1 && obj.k1.k2 && obj.k1.k2.k3){    console.log(obj.k1.k2.k3); }else{    console.log('值為空') }