caesarEncrypt(msg, key): Using Caesar cipher to encrypt the msg with key; returning the ciphertext. The parameter msg is the plaintext (string type); the parameter key is the encryption key value (integer type); the return value is the ciphertext (string type).

caesarDecrypt(msg, key): Using Caesar cipher to decrypt the msg with key; returning the plaintext. The parameter msg is the ciphertext (string type); the parameter key is the decryption key value (integer type); the return value is the plaintext (string type).

This needs to be done in python with two functions; one for encrypting, the other for decrypt