def itemsReceived(event):
    """
        Called when an items notification has been received for a node.

        An item can be an element named C{item} or C{retract}. Respectively,
        they signal an item being published or retracted, optionally
        accompanied with an item identifier in the C{id} attribute.

        @param event: The items event.
        @type event: L{ItemsEvent<wokkel.pubsub.ItemsEvent>}
        """
