How to access the inside function

Tell us what’s happening:

why isn’t the inside function being called?

Your code so far

function addTogether(one, two) {
if(!Number.isInteger(one) || !Number.isInteger(two)) return undefined;
if(two) return (one+two);

function inside(num){
  if(!Number.isInteger(num)) return undefined;
  return (one+num);
return inside;


Your browser information:

User Agent is: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36.

Challenge: Arguments Optional

Link to the challenge:

If two is undefined, then the first case will have executed and your addTogether function will return undefined. Otherwise it will satisfy the second condition and return one + two.