def to_json(self):
    """Returns writer state to serialize in json.

    Returns:
      A json-izable version of the OutputWriter state.
    """
    raise NotImplementedError("to_json() not implemented in %s" +
                              self.__class__)
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/mapreduce/output_writers.py/OutputWriter.to_json/operator `%` -> `+`