/**
 * Foo Object
 */
var Foo = function (config) {
  var options = JSON.parse( JSON.stringify(config) );
  options.items = [];
  _.extend(this, options);
};

Foo.prototype.set = function (config) {
  _.extend(this, config);
  return this;
};

Foo.prototype.addItem = function (items) {
  items = _(items).isArray() ? items : [items];
  this.items = _.union(this.items, items);
  return this;
};