function Player() { } Player.prototype.play = function(song) { this.currentlyPlayingSong = song; this.isPlaying = true; }; Player.prototype.pause = function() { this.isPlaying = false; }; Player.prototype.resume = function() { if (this.isPlaying) { throw new Error("song is already playing"); } this.isPlaying = true; }; Player.prototype.makeFavorite = function() { this.currentlyPlayingSong.persistFavoriteStatus(true); };