new_contents: 
  # References: 
  #  - https://stackoverflow.com/questions/537542/how-can-i-create-multiple-hashes-of-a-file-using-only-one-pass
  #  - https://stackoverflow.com/questions/16694907/how-to-download-large-file-in-python-with-requests-py
  #  - https://gist.github.com/Zireael-N/ed36997fd1a967d78cb2
  
subject: Create url_to_prefetch.py