intial fix for arrowhead

well commit history is gone which is awesome.  I liked command line git better anyways
Feel free to argue on this, but the hip ruby way of doing this (and we are ruby brogrammers not just programmers here) would be to name this method as a noun and your argument isn't really a shape as much as it is a `key`. I know that our public contract in `classify` names the parameter `shape`, but you can take this opportunity to make this a private_class_method and name the arg whatever makes things more obvious.

Making it private will allow you to have more control.