@classmethod
  def get_filenames(cls, mapreduce_state):
    """Obtain output filenames from mapreduce state.

    Args:
      mapreduce_state: an instance of model.MapreduceState

    Returns:
      list of filenames this writer writes to or None if writer
      doesn't write to a file.
    """
    raise NotImplementedError("get_filenames() not implemented in %s" + cls)
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/mapreduce/output_writers.py/OutputWriter.get_filenames/operator `%` -> `+`