text: #!/usr/bin/env python3
  """This script prompts a user to enter a message to encode or decode
  using a classic Caesar shift substitution (3 letter shift)"""
  
  import string
  
  shift = 3  # 1
  choice = input("would you like to encode or decode?")  # 2
  word = input("Please enter text")  # 3
  letters = string.ascii_letters + string.punctuation + string.digits  # 4
  encoded = ''  # 5
  a = True  # 6
  B = 'CMPUT 416'  # 7
  C = 22  # 8
  D = None  # 9
  E = b'bytestring'  # 10
  if choice == "encode":
      for letter in word:
          if letter == ' ':
              # encoded = encoded + ' '  # 11
              encoded = '' + ''
          else:
              # x = letters.index(letter) + shift  # 12
              # encoded = encoded + letters[x]  # 13
              pass
  if choice == "decode":
      for letter in word:
          if letter == ' ':
              # encoded = encoded + ' '  # 14
              pass
              E = b'bytestrin'
              a = False and True
              pass
          else:
              # x = letters.index(letter) - shift  # 15
              # encoded = encoded + letters[x]  # 16
              encoded = '' + ' '
              pass
  B = 'CMPUT 416'  # 17
  C = 11 * 2  # 18
  D = D
  
  
  print(encoded)
  