new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  import os
  
  
  def get_file_path_list(dataset_meta):
      """
      A helper function that accepts the path of enron dataset and
      return all the email file paths.
      """
      email_file_path_list = []
  
      for subdir in dataset_meta['subdirs']:
          for file in os.listdir(subdir['spam_path']):
              email_file_path_list.append(
                  os.path.join(subdir['spam_path'], file)
              )
  
          for file in os.listdir(subdir['ham_path']):
              email_file_path_list.append(
                  os.path.join(subdir['ham_path'], file)
              )
  
  
  def split_dataset(file_path_list):
      """
      A helper function that accepts a list of file path and split it
      into training data and test data.
      """
      pass
  
subject: Add utils.