code: def find_mapreduce_yaml(status_file=__file__):
    
    checked = set()
    yaml = _find_mapreduce_yaml(os.path.dirname(status_file), checked)
    if not yaml:
      yaml = _find_mapreduce_yaml(os.getcwd(), checked)
    return yaml
docs: Traverse directory trees to find mapreduce.yaml file.
  
    Begins with the location of status.py and then moves on to check the working
    directory.
  
    Args:
      status_file: location of status.py, overridable for testing purposes.
  
    Returns:
      the path of mapreduce.yaml file or None if not found.