def _use_datastore(self, key, options=None):
    flag = ContextOptions.use_datastore(options)
    if flag is None:
      flag = self._datastore_policy(key)
    if flag is None:
      flag = ContextOptions.use_datastore(self._conn.config)
    if flag is None:
      flag = True
    return flag
Return whether to use the datastore for this key.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/ndb/context.py/Context._use_datastore