Returning by reference. Parentheses around a return variable.

http://php.net/manual/en/function.return.php

"You should never use parentheses around your return variable when returning by reference, as this will not work. You can only return variables by reference, not the result of a statement. If you use return ($a); then you're not returning a variable, but the result of the expression ($a) (which is, of course, the value of $a)."

I tried this piece of code and it works:

What code example would explain it better (show what the note is talking about)?

Thanks.