function Animal(name) {
  this.name = name
  
  this.makeSound = (sound) => {
    return sound
  }
}
function Cat(name) {
  Animal.call(this, name)
  
  this.makeSound = () => {
    return 'Meow'
  }
}
function Dog(name) {
  Animal.call(this, name)
  
  this.makeSound = () => {
    return 'Woof'
  }
}

let fluffy = new Cat('Fluffy')
fluffy.makeSound()

let sheeba = new Dog('Sheeba')
sheeba.makeSound()