Online PHP editor | output for rZlT6

<?php /* Challenge 1: Modify Test::$secret before it's output. Rules:: 1. No use of Reflection API / runkit extension 2. No stopping execution before Test::run() 3. No Exceptions or PHP errors / warnings notices allowed Hints: 1. Caesar 2. Magic methods 3. Requires a new feature of PHP 5.4 */ class Test { private $secret = 'Nyy lbhe Onfr ner orybat gb hf.'; private $callback; final public function run() { call_user_func($this->callback); return $this->secret . PHP_EOL; } public function __set($k, $v) { $key = $v[($v[$v])]; // $v is some kind of weird array $value = $v(); // and a callback! $this->{$key} = $value; } } class TestM extends Test { public function run(&$obj){ $obj->secret = "HELLO WORLD"; } } $test = new Test; // start editing here $testM = new TestM; $testM->run($test); // end editing here echo $test->run();