Can't pickle RerankingParser: attribute lookup RerankerModel on importlib._bootstrap failed

[halfak]

$ python
Python 3.5.1+ (default, Mar 30 2016, 22:46:26) 
[GCC 5.3.1 20160330] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from bllipparser import RerankingParser
>>> bllip_rrp = RerankingParser.fetch_and_load('WSJ-PTB3')
>>> import pickle
>>> len(pickle.dumps(bllip_rrp))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
_pickle.PicklingError: Can't pickle <class 'JohnsonReranker.RerankerModel'>: attribute lookup RerankerModel on importlib._bootstrap failed