def __pos__(self):
    return datastore_query.PropertyOrder(self._name)
Function that can be curried to provide the source accessor or DB column name for the m2m table
dataset/ETHPy150Open GoogleCloudPlatform/datastore-ndb-python/ndb/model.py/Property.__pos__--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/models/fields/related.py/ManyToManyField._get_m2m_attr