@classmethod
  def validate(cls, mapper_spec):
    """Validates mapper specification.

    Output writer parameters are expected to be passed as "output_writer"
    subdictionary of mapper_spec.params. To be compatible with previous
    API output writer is advised to check mapper_spec.params and issue
    a warning if "output_writer" subdicationary is not present.
    _get_params helper method can be used to simplify implementation.

    Args:
      mapper_spec: an instance of model.MapperSpec to validate.
    """
    raise NotImplementedError("validate() not implemented in %s" + cls)
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/mapreduce/output_writers.py/OutputWriter.validate/operator `%` -> `+`