def atbash_cipher_encryptor_decryptor(message: str) -> str:
    """Encrypts and decrypts a given message using an AtBash Cipher (substitutes a letter of the plaintext 
    alphabet with the corresponding letter of the reversed alphabet).

    a <-> z
    b <-> y
    c <-> x

    Args:
        message (str): Message to be encrypted or decrypted.

    Returns:
        encrypted_decrypted_message (str): Encrypted or decrypted message.
    """
    N = ord("z") + ord("a")
    encrypted_decrypted_message = "".join([chr(N - ord(char)) for char in message])

    return encrypted_decrypted_message