input: from Crypto.Cipher import AES
  
  
  def encrypt(plaintext):
      """ Encrypts a given string using the AES cipher in ECB mode with a predefined key.
      >>> encrypt(b'mysecretmessage')
      b'\x92}\xf2S\xa8t\xac\x9eo\xa1\xa9vf\xc4\xc7\x83'
      >>> encrypt(b'supersecret')
      b'\xe5Q\xc4DV\xc6\xb5\x1bI -\xdf\xb0LA'
      """
      key = b'Sixteen byte key'
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.encrypt(plaintext)
  
  
  def decrypt(ciphertext):
      """ Decrypts a given ciphertext using the AES cipher in ECB mode with the same predefined key.
      >>> decrypt(b'\x92}\xf2S\xa8t\xac\x9eo\xa1\xa9vf\xc4\xc7\x83')
      b'mysecretmessage'
      >>> decrypt(b'\xe5Q\xc4DV\xc6\xb5\x1bI -\xdf\xb0LA')
      b'supersecret'
      """
      key = b'Sixteen byte key'
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.decrypt(ciphertext)
output:     key = b'Sixteen byte key'
      cipher = AES.new(key, AES.MODE_ECB)
      return cipher.decrypt(ciphertext)