const Parent = declare(null, {
    init: function (params) {
      declare.mixin(this,params);
      return this;
    },
    sayName: function () {
      console.log(this.name);
      return this;
    },
});

const Child = declare(Parent, {
    init: function () {
      Parent.prototype.init.apply(this,arguments); // strict mode
      // this.inherited(arguments); // non strict mode
      return this;
    },
    sayAge: function () {
      console.log(this.age);
      return this;
    },
});

const boy = new Child({
  name: "Raoh",
  age: 20,
});

boy.sayName().sayAge();
// Raoh
// 20