input: Write a python function to encrypt a message using XOR and then decrypt it back to the original message using the given key.
  assert encrypt('hello', 'key12') == [3, 6, 9, 7, 4]
  assert decrypt([3, 6, 9, 7, 4], 'key12') == 'hello'
  assert encrypt('world', 'key34') == [4, 7, 10, 8, 5]
  assert decrypt([4, 7, 10, 8, 5], 'key34') == 'world'
output: def encrypt(message, key):
      return [ord(m) ^ ord(k) for m, k in zip(message, key * (len(message) // len(key)) + key[:len(message) % len(key)])]
  
  def decrypt(encrypted_message, key):
      return ''.join(chr(e ^ ord(k)) for e, k in zip(encrypted_message, key * (len(encrypted_message) // len(key)) + key[:len(encrypted_message) % len(key)]))