text: #!/usr/bin/env python
  """Base pipelines."""
  
  
  from mapreduce.lib import pipeline
  
  from mapreduce import parameters
  
  # pylint: disable=g-bad-name
  
  
  class PipelineBase(pipeline.Pipeline):
    """Base class for all pipelines within mapreduce framework.
  
    Rewrites base path to use pipeline library bundled with mapreduce.
    """
  
    def start(self, **kwargs):
      if "base_path" not in kwargs:
        kwargs["base_path"] = parameters._DEFAULT_PIPELINE_BASE_PATH
      return pipeline.Pipeline.start(self, **kwargs)
  
  
  class _OutputSlotsMixin(object):
    """Defines common output slots for all MR user facing pipelines.
  
    result_status: one of model.MapreduceState._RESULTS. When a MR pipeline
      finishes, user should check this for the status of the MR job.
    """
  
    output_names = ["result_status"]
  