Thanks for the question, in some cases you might want to use the value you popped from the array but here, it’s just for visual’s sake. So, if it doesn’t fit into your need, don’t bother to return any value. Also, its good practice to adhere to the single responsibility principle where your function does just one thing. So, feel free not to return an Int value from the function 😁. The cited example is for illustration purpose to convey what mutating function is all about in Swift.