Make the below code work (Asked in amazon interview)

myNumber.js

/*
Make the below function calling work:

  myNumber(10)
    .subtract(3)
    .add(10,1,3)
    .value();

    myNumber(10)
    .add(7)
    .value();
*/


function myNumber(a) {
	var resp = a;
	return {
		add: function(...args) {
			for(i in args) {
				resp += args[i];
			}
			return this;
		},
		subtract: function(...args) {
			for(i in args) {
				resp -= args[i];
			}
			return this;
		},
		value: function(){
        	return resp;
		}
	}
}

myNumber(10).subtract(3).add(10,1,3).value();