refactored Decorator pattern

Structural/Decorator/ExtraBed.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace DesignPatterns\Structural\Decorator;
+
+class ExtraBed extends BookingDecorator
+{
+    private const PRICE = 30;
+
+    public function calculatePrice(): int
+    {
+        return $this->booking->calculatePrice() + self::PRICE;
+    }
+
+    public function getDescription(): string
+    {
+        return $this->booking->getDescription() . ' with extra bed';
+    }
+}