Are you a PHP 5 guru?

If you are able to answer the following questions, you are certainly one of them! Consider the following script:
<?php
error_reporting(E_ALL | E_STRICT);
$test[isset($test)] = $test;
var_dump($test);
?>

1. How many notices are displayed?
2. What is the output?

Ok, you replied with:

1. 1 notice (Notice: Undefined variable: test in ...)

2. array(1) {
   [0]=>
   NULL
   }

Congratulations! You just failed your Zend Engineer Certification.
Joke aside, correct answers were:

1. 0 notice

2. array(1) {
   [0]=>
   array(1) {
   [0]=>
   *RECURSION*
   }
   }

Well, in PHP 4 you would be in the right, but PHP 5 introduces a new feature that let you construct a kind of recursive array... More interesting is that if you used an isset on the right part of the assignment it would return you false!