class Animal {

    constructor (name, fly=false, sound) {

        this.name = name

        this.fly = fly

        this.sound = sound

    }

    canFly (fly) {

      if(this.fly) {

        return 'goes up up in the sky'

      }

      return 'stays on the ground'

    }

    talk (sound) {

      return this.sound;

    }

    describe () {

console.log(`${this.name}

${this.canFly()}

and shouts ${this.talk()}`)

    }

}

​

var bird = new Animal('birdy', true, 'tchirp')

var cat  = new Animal('kitty', false, 'miao')

var strangething  = new Animal()

​

bird.describe()

cat.describe()

strangething.describe()