input: Write a function to create an application in Python for encryption and decryption of strings. The application should take a string as input, and use the AES cipher text algorithm to encrypt the string. The function should return the encrypted string and allow for decryption of the same string.
  assert encrypt("Hello World")==b'\xf6U\xf6A_\xabuT{_\xcdd^m\x948\r\xb2'
  assert decrypt(b'\xf6U\xf6A_\xabuT{_\xcdd^m\x948\r\xb2')==b'Hello World'
output: import base64
  from Crypto.Cipher import AES
  from Crypto.Util.Padding import pad, unpad
  
  def encrypt(text):
      key = b'Sixteen byte key'
      cipher = AES.new(key, AES.MODE_CBC)
      ct_bytes = cipher.encrypt(pad(text.encode(), AES.block_size))
      return base64.b64encode(cipher.iv + ct_bytes)
  
  def decrypt(enc):
      key = b'Sixteen byte key'
      enc = base64.b64decode(enc)
      iv = enc[:AES.block_size]
      cipher = AES.new(key, AES.MODE_CBC, iv)
      return unpad(cipher.decrypt(enc[AES.block_size:]), AES.block_size)