<?php
class Animal
{
    public function __construct(public string $name)
    {
    }

    public function describe(): string
    {
        return $this->name . " makes a sound.";
    }
}

class Dog extends Animal
{
    public function fetch(): string
    {
        return $this->name . " fetches the ball.";
    }
}

$d = new Dog("Rex");
echo $d->describe(); // Rex makes a sound.
echo "\n";
echo $d->fetch();    // Rex fetches the ball.
?>