      /**
       * Fired when an item is deselected
       *
       * @event iron-deselect
       */

      /**
       * Fired when the list of selectable items changes (e.g., items are
       * added or removed). The detail of the event is a list of mutation
       * records that describe what changed.
       *
       * @event iron-items-changed
       */

    properties: {

      /**
       * If you want to use an attribute value or property of an element for
       * `selected` instead of the index, set 