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
Gets the name of the carrier for the given PhoneNumber object only when
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/ndb/context.py/Context._use_datastore--crossover with--dataset/ETHPy150Open daviddrysdale/python-phonenumbers/python/phonenumbers/carrier.py/safe_display_name