User expansion on paths.

I don't really like the tests I've got here; they were what I could bang out in a couple minutes. Let me know if you have a better approach, and I'll fix them up.

*a cute animal picture for your troubles…*

[![Baby Tapir!](http://33.media.tumblr.com/8afaeee025ef5af7effcccb205673b16/tumblr_na5dw3gyWW1s5iqc4o3_1280.jpg)](http://zooborns.tumblr.com/post/94438161679/baby-tapir-noses-in-at-chester-zoo-zoo-keepers)