Totally agree. As we've discussed in the meeting, the MetadataMap used here is slightly different from the QIIME's one (e.g. the id).

I can add it in this PR, importing from QIIME.util and then we can change that import later on. I'll also change the function names and everything else that we need to change from the current code.

Is this blocking something? I can get this changes for next meeting, but if this is blocking something I can get it earlier.