Set collection to saved/unsaved on change

gistfile1.js

var CookieCollection = Backbone.Collection.extend({
  saved : false,
  model : Cookie,

  initialize: function() {
    this.bind('add',    this.setUnsaved, this);
    this.bind('remove', this.setUnsaved, this);
  },

  setUnsaved: function() {
    this.saved = false
  }
});

var cookies = new CookieCollection;