me has volado la cabeza amigo jajaja, saludos !!

wow that's good

do you have a right example how to solve it with closures?

I think it's more readable than some think; if the s in elaborated on

Is this better though? I'd wonder if it's faster or slower?

amazing!

Wrong solution - no closure used. Yes this solution works, but the task was to use closure.

No, it's not.

You just deleted the equal signs. Did you really save that much space?
However, it's still not best practice for me. It's just a trick.

Is this really using the concept of closures though?

While the solution is quite clever, it's not the most readable piece ever, at least for me.