input: def encrypt_shift(s: str):
      """
      produces a new string by moving each letter 5 positions forward in the alphabet.
      """
      return "".join([chr(((ord(ch) + 5 - ord("a")) % 26) + ord("a")) for ch in s])
  
  
  def decrypt_shift(s: str):
      """
      accepts a string that has been encrypted with the encrypt_shift function and returns the original string.
      """
output:     return "".join([chr(((ord(ch) - 5 - ord("a")) % 26) + ord("a")) for ch in s])