Recursive function returning undefined

Question

I have a recursive function for returning nested objects. However when I assign it to a variable and then call the variable it returns undefined. Any idea as to what the problem might be? Thanks!
function iterObj(obj){
for (var key in obj){
console.log (key + ":" + obj[key]);
if (obj[key] !== null && typeof obj[key] === 'object'){
return iterObj(obj[key]);
}
}
}
var solo = iterObj(argument) // nested objects
solo // undefined
https://code.sololearn.com/W675Ao227f7B/?ref=app

Answer 1

"argument" is not defined in your js

Answer 2

Yeah I know the argument is just a pseudo argument. Right now there's no real argument passed in. I just wanted to know if there was anything wrong with the structure. Thanks!