public void Decryptor()
        {
            string expected = "xyz";
            string actual   = CaesarCypher.Decryptor("zab", 2);

            Assert.AreEqual(expected, actual);
        }
    static void Main()
    {
        string sentence          = "Hello, XYZxyz";
        string sentenceEncrypted = CaesarCypher.Encrypt(sentence);

        Console.WriteLine(sentenceEncrypted);

        Console.WriteLine(CaesarCypher.Decrypt(sentenceEncrypted));
    }