new_contents: #!/usr/bin/env python3
  
  from sys import argv
  
  def chiper(string):
      return ''.join(cipher_dict[x] for x in string)
  
  def dechipher(string):
      return ''.join(decipher_dict[x] for x in string)
  
  
  cipher_dict = dict(zip("abcdefghijklmnopqrstuvwxyz ", " abcdefghijklmnopqrstuvwxyz"))
  decipher_dict = {v: k for k, v in cipher_dict.items()}
  
  s = argv[1]
  
  ciphered = chiper(s)
  dechiphered = dechipher(ciphered)
  print('input = "{}"'.format(s))
  print('chiphered = "{}"'.format(ciphered))
  print('dechiphered = "{}"'.format(dechiphered))
  
subject: add it-security/cipher.py