new_contents: import uuid, hashlib
  
  >>> uuid.uuid4().hex # generate uuid
  >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'other').hex
  
  >>> hashlib.sha224(b"saya").hexdigest()
  'e21e189dbc4df1cf36ebf6f926a29e3d893be9e2a99546d49a039d0d'
  >>> h = hashlib.sha224(b"saya").hexdigest()
  >>> hashlib.sha224(b"saya").hexdigest() == h
  True
  >>> hashlib.sha224(b"saya").hexdigest()
  'e21e189dbc4df1cf36ebf6f926a29e3d893be9e2a99546d49a039d0d'
  >>> 
  
subject: Create uuid-hashlib.py