Image gallery navigation bar
You can use the next and previous attributes from the image object
to add a simple navbar for your image for a simple slideshow
<a href="previous.jpg.htm" py:attr="image.previous+'.htm'">[Previous]</a> <img src="image.jpg" py:attr="image.url"> <a href="next.jpg.htm" py:attr="image.next+'.htm'">[Next]</a>