@staticmethod
  def default_datastore_policy(key):
    flag = None
    if key is not None:
      modelclass = model.Model._kind_map.get(key.kind())
      if modelclass is not None:
        policy = getattr(modelclass, '_use_datastore', None)
        if policy is not None:
          if isinstance(policy, bool):
            flag = policy
          else:
            flag = policy(key)
    return flag
Default datastore policy.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/ndb/context.py/Context.default_datastore_policy