php i don't even.php

    <?php
    class Foo
    {
        protected $default='default';
        public function test()
        {
            $this->default = 'not default';
            echo $this->addChild(),"\n";
            
        } 
    
        protected function addChild($level=0)
        {
            if($level > 10)
            {
                return 'Done';
            }
            $level++;
            echo "Incremeneted to $level\n";
            echo '    ' , $this->default,"\n";
            return self::addChild($level);
        }    
    }

    $object = new Foo;
    $object->test();