class Pet 
{
    public $name;
    
    function __construct($pet_name) 
    {
        $this->name = $pet_name;
    }
    
    function eat()   { /* ... */ }
    function sleep() { /* ... */ }
    function play()  { /* ... */ }
}

class Cat extends Pet 
{
    function play() 
    {
        parent::play();
    }
}

$cat = new Cat('Bucky');
$pet = new Pet('Rob');

$cat->eat();
$pet->sleep();

// Delete the objects
unset($cat, $pet);