iron-pages is used to select one of its children to show. One use is to cycle through a list of
children "pages".
Example:
<iron-pages selected="0">
<div>One</div>
<div>Two</div>
<div>Three</div>
</iron-pages>
<script>
document.addEventListener('click', function(e) {
var pages = document.querySelector('iron-pages');
pages.selectNext();
});
</script>