code: function(e) {
              var k = this._out(e.key);// undefined if key is not in the namespace
              if ((k && (!key || k === key)) && // match key if listener has one
                  (!e.storageArea || e.storageArea === this._area)) {// match area, if available
                  return fn.call(this, _.event.call(this, k, e));
              }
          }
docs: no key === all keys