Anyone familiar with Python (the most commonly taught introductory programming language, and, most importantly, [esr-approved](http://catb.org/~esr/faqs/hacker-howto.html)) should be used to to [negative indices](http://wordaligned.org/articles/negative-sequence-indices-in-python).
(Nim has good reason for using `^` instead of `-`, but the idea is the same.) IMHO, avoiding it (ex `test[6 ..< test.len`) is just bad style.
