'Persist that a user\'s devices have been updated, and which hosts
(if any) should be poked.'

@defer.inlineCallbacks
def add_device_change_to_streams(self, user_id, device_ids, hosts):

    with self._device_list_id_gen.get_next() as stream_id:
        (yield self.runInteraction('add_device_change_to_streams', self._add_device_change_txn, user_id, device_ids, hosts, stream_id))
    defer.returnValue(stream_id)
