Export the preorder so we can walk the taxonomy.
Export the preorder so we can walk the taxonomy.

I don't know if this is the "right" way though.

Also this could be a list of integers, except that it has two keys which
are strings: "root" and "root_preorder".

OpenTreeOfLife/peyotl,OpenTreeOfLife/peyotl,mtholder/peyotl,mtholder/peyotl