old_contents: # Vigenere Cipher (Polyalphabetic Substitution Cipher)
  # https://www.nostarch.com/crackingcodes/ (BSD Licensed)
  
  from books.CrackingCodesWithPython.pyperclip import copy
  
  LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  
  def main():
      # This text can be downloaded from https://www.nostarch.com/crackingcodes/:
      myMessage = """Alan Mathison Turing was a British mathematician, logician, cryptanalyst, and computer scientist."""
      myKey = 'ASIMOV'
      myMode = 'encrypt' # Set to either 'encrypt' or 'decrypt'.
  
      if myMode == 'encrypt':
          translated = encryptMessage(myKey, myMessage)
      elif myMode == 'decrypt':
          translated = decryptMessage(myKey, myMessage)
  
      print('%sed message:' % (myMode.title()))
      print(translated)
      copy(translated)
      print()
      print('The message has been copied to the clipboard.')
  
  
  def encryptMessage(key, message):
      return translateMessage(key, message, 'encrypt')
  
  
  def decryptMessage(key, message):
      return translatedMessage(key, message, 'decrypt')
  
  
  def translateMessage(key, message, mode):
      translated = [] # Stores the encrypted/decrypted message string.
  
      keyIndex = 0
      key = key.upper()
  
      for symbol in message: # Loop through each symbol in message.
          num = LETTERS.find(symbol.upper())
          if num != -1: # -1 means symbol.upper() was not found in LETTERS.
              if mode == 'encrypt':
                  num += LETTERS.find(key[keyIndex]) # Add if encrypting.
              elif mode == 'decrypt':
                  num -= LETTERS.find(key[keyIndex]) # Subtract if decrypting.
  
              num %= len(LETTERS) # Handle any wraparound.
  
              # Add the encrypted/decrypted symbol to the end of translated:
              if symbol.isupper():
                  translated.append(LETTERS[num])
              elif symbol.islower():
                  translated.append(LETTERS[num].lower())
  
              keyIndex += 1 # Move to the next letter in the key.
              if keyIndex == len(key):
                  keyIndex = 0
          else:
              # Append the symbol without encrypting/decrypting:
              translated.append(symbol)
  
      return ''.join(translated)
  
  
  # If vigenereCipher.py is run (instead of imported as a module), call
  # the main() function:
  if __name__ == '__main__':
      main()
new_contents: # Vigenere Cipher (Polyalphabetic Substitution Cipher)
  # https://www.nostarch.com/crackingcodes/ (BSD Licensed)
  
  from books.CrackingCodesWithPython.pyperclip import copy
  
  LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  
  def main():
      # This text can be downloaded from https://www.nostarch.com/crackingcodes/:
      myMessage = """Alan Mathison Turing was a British mathematician, logician, cryptanalyst, and computer scientist."""
      myKey = 'ASIMOV'
      myMode = 'encrypt'  # Set to either 'encrypt' or 'decrypt'.
  
      if myMode == 'encrypt':
          translated = encryptMessage(myKey, myMessage)
      elif myMode == 'decrypt':
          translated = decryptMessage(myKey, myMessage)
  
      print('%sed message:' % (myMode.title()))
      print(translated)
      copy(translated)
      print()
      print('The message has been copied to the clipboard.')
  
  
  def encryptMessage(key, message):
      return translateMessage(key, message, 'encrypt')
  
  
  def decryptMessage(key, message):
      return translatedMessage(key, message, 'decrypt')
  
  
  def translateMessage(key, message, mode):
      translated = []  # Stores the encrypted/decrypted message string.
  
      keyIndex = 0
      key = key.upper()
  
      for symbol in message:  # Loop through each symbol in message.
          num = LETTERS.find(symbol.upper())
          if num != -1:  # -1 means symbol.upper() was not found in LETTERS.
              if mode == 'encrypt':
                  num += LETTERS.find(key[keyIndex])  # Add if encrypting.
              elif mode == 'decrypt':
                  num -= LETTERS.find(key[keyIndex])  # Subtract if decrypting.
  
              num %= len(LETTERS)  # Handle any wraparound.
  
              # Add the encrypted/decrypted symbol to the end of translated:
              if symbol.isupper():
                  translated.append(LETTERS[num])
              elif symbol.islower():
                  translated.append(LETTERS[num].lower())
  
              keyIndex += 1  # Move to the next letter in the key.
              if keyIndex == len(key):
                  keyIndex = 0
          else:
              # Append the symbol without encrypting/decrypting:
              translated.append(symbol)
  
      return ''.join(translated)
  
  
  # If vigenereCipher.py is run (instead of imported as a module), call
  # the main() function:
  if __name__ == '__main__':
      main()
  
subject: Update vigenereCipher: fixed PEP8 spacing