No last property for "set" any more?
<p>thanks for your time and attention on this beginner's issue</p>

<p>The book I've read claims that "You can use the first and last propeties, which return one of the elements in the set"</p>

<p>However, I've tried it and seems it is not working. I would very appreciate if someone can explain it for me. </p>

<p><a href="https://i.stack.imgur.com/smGlw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/smGlw.png" alt="enter image description here"></a></p>