new_contents: #!/usr/bin/env python
  
  import glob
  import os.path
  import random
  
  
  def pick_random(directory, k=None):
      """Pick randomly some files from a directory."""
      all_files = glob.glob(os.path.join(directory, '*'))
      random.shuffle(all_files)
      return all_files if k is None else all_files[:k]
  
subject: Add util module