Problem completing last challange

Tell us what’s happening:
the last challenge [The sum function uses the ... spread operator on the args parameter.]
help me to complete this condition has not completed yet.

Your code so far

const sum = (function() {
  "use strict";
  return function sum(...x) {
    const args = [...x];
    return args.reduce((a, b) => a + b, 0);
console.log(sum(1, 2, 3)); // 6

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36.

I will give you a hint, this line:
const args = [...x];
Is not needed to solve this problem.