code: def _getModelCheckpointFilePath(checkpointDir):
      
      path = os.path.join(checkpointDir, "model.data")
      path = os.path.abspath(path)
      return path
docs: Return the absolute path of the model's checkpoint file.
  
      :param checkpointDir: (string)
             Directory of where the experiment is to be or was saved
      :returns: (string) An absolute path.