Regular and Inverted Loops
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/26474941@N00">Ed Brambley</a> from Cambridge, UK
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/edbrambley/4260515142/">Regular and Inverted Loops</a>