http://schema.org/docs/schema_org_rdfa.html is not in the same sequence as (or maybe should now point to /latest/ or /current/ or /2.0/?):

• https://github.com/schemaorg/schemaorg/blob/sdo-ganymede/data/releases/2.0/schema.rdfa

RDFLib collections.OrderedDicts? (There's a CPython OrderedDict slated for Python 3.5)