test2.php

<?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();
}
// start editing here

class Answer implements AnswerInterface{
    private $theanswer;
    
    public function __construct(){}
    
    public function get(){
        $this->theanswer = 2;
        return $this;
    }
    
    public function the(){
        $this->theanswer += 2;
        return $this;
    }
    
    public function answer(){
        return $this;
    }
    
    public function __toString() {
        return (string)$this->theanswer;
    }
}

// end editing here
$answer = new Answer;
$question = new Question($answer);