<?php
interface Shape
{
    public function area(): float;
}

class Circle implements Shape
{
    public function __construct(private float $radius)
    {
    }

    public function area(): float
    {
        return 3.14159 * $this->radius ** 2;
    }
}

class Square implements Shape
{
    public function __construct(private float $side)
    {
    }

    public function area(): float
    {
        return $this->side ** 2;
    }
}

$shapes = [new Circle(2), new Square(3)];
foreach ($shapes as $shape) {
    echo $shape->area() . "\n"; // 12.56636 then 9
}
?>