Not sure, because if QIIME imports from here then QIIME is still GPL. 

This one might be a relatively straightforward copy/paste, the only nightmare is `Sequence`, but it appears to only be used once [here](https://github.com/pycogent/pycogent/blob/master/cogent/parse/flowgram.py#L175). That being said, one relatively straightforward thing has all kinds of demons laying around, and is yet another thing on top of the things to do.

I dont know any other way around this, basically importing from cogent is something that I believe needs to be avoided, otherwise brokit is GPL unless I'm misunderstanding something.