Online PHP editor | output for 4366W

<?php /* Challenge 2: Implement AnswerInterface and get Question to echo "4". */ class Question { public function __construct(AnswerInterface $answer) { echo "What is 2 + 2?\n"; $answer = $answer->get()->the()->answer(); if ($answer instanceof AnswerInterface) { echo $answer . PHP_EOL; } } } interface AnswerInterface { public function get(); public function the(); public function answer(); } class Answer implements AnswerInterface { private $answer = (int) 4; public function get() { return $this; } public function the() { return $this; } public function answer() { return $this->answer; } } $answer = new Answer; $question = new Question($answer);