<!-- BEGIN COPY / PASTE -->
        class Animal {
            constructor(name) {
                this.name = name;
            }

            speak() {
                console.log(`${this.name} makes a noise.`);
            }
        }

        class Dog extends Animal {
            speak() {
                console.log(`${this.name} barks.`);
            }
        }

        const dog = new Dog('Rex');
        dog.speak(); // Output: Rex barks.
        <!-- END COPY / PASTE -->