$GLOBALS example script on php.net

Dear all, I was reading this page http://php.net/manual/en/reserved.variables.globals.php and I found the following script there : ---- Here's a function which returns an array of all user defined global variables: <?php function globals() { $globals = $GLOBALS; foreach (array( 'GLOBALS', '_ENV', 'HTTP_ENV_VARS', '_POST', 'HTTP_POST_VARS', '_GET', 'HTTP_GET_VARS', '_COOKIE', 'HTTP_COOKIE_VARS', '_SERVER', 'HTTP_SERVER_VARS', '_FILES', 'HTTP_POST_FILES', '_REQUEST' ) as $var) { unset($globals[$var]); } return $globals; } ?> I think that this script UNSETS each supergobal variable,but page says that it returns ALL user defined vars ? Can some one tell me how that is ? Thank you, Ashim