/* Mixin class. */var Mixin = function() {};Mixin.prototype = {  serialize: function() {    var output = [];    for(key in this) {      output.push(key + ': ' + this[key]);    }    return output.join(', ');  }};augment(Author, Mixin);var author = new Author('Ross Harmes', ['JavaScript Design Patterns']);var serializedString = author.serialize();