'Constructor.
Args:
default_model: If an implementation for the kind cannot be found, use
this model class.  If none is specified, an exception will be thrown
(default).
id_resolver: A datastore_pbs.IdResolver that can resolve
application ids. This is only necessary when running on the Cloud
Datastore v1 API.'

def __init__(self, default_model=None, id_resolver=None):

    try:
        super(ModelAdapter, self).__init__(id_resolver)
    except:
        pass
    self.default_model = default_model
    self.want_pbs = 0
