title: this.variable is undefined
body: <p>Hi there I am getting the error this._radioButtons is undefined ( the code between **)in the following snippet. Is there something about the closures that I am missing here?</p>
  
  <pre><code>_adjustChoices: function(choices) {
              // TODO Tear down all the old radion buttons and their change handlers.
              debugger;
              this._radioButtons = [];
              this._changeHandlers = [];
              array.forEach(choices, function(choice) {
                  var radioButton = new RadioButton(lang.mixin({
                      name: this._clusterName
                  }, choice));
                  **this._radioButtons.push(radioButton);**
                  this._changeHandlers.push(connect.connect, radioButton, "onChange", lang.hitch(this, function(value) {
                      // TODO Figure out which radio button is selected and get its value.
                      //var radioButton = ????;
                      this.set("value", radioButton.get("checked"));
                  }));
              });
          },
  </code></pre>