old_contents: import os, binascii
  
  def unique_hex(length=8):
      return binascii.hexlify(os.urandom(int(length/2))).decode()
  
  
  if __name__ == '__main__':
      print(unique_hex())
  
  
new_contents: import os, binascii
  
  def unique_hex(byte_length=4):
      return binascii.hexlify(os.urandom(byte_length)).decode()
  
  
  if __name__ == '__main__':
      print(unique_hex())
  
  
subject: change utils.unique_hex's length to be a spec for bytes