code: def testCipher(self):
      self.assertEqual(cipher.rot13("Hello world!"), "Uryyb jbeyq!")
      self.assertEqual(
          cipher.caesar_encode(13, "Hello world!"), "Uryyb jbeyq!"
      )
      self.assertEqual(
          cipher.caesar_decode(13, "Uryyb jbeyq!"), "Hello world!"
      )
  
      self.assertEqual(
          cipher.caesar_encode(1, "Hello world!"), "Ifmmp xpsme!"
      )
      self.assertEqual(
          cipher.caesar_decode(1, "Ifmmp xpsme!"), "Hello world!"
      )
  
imports: from fire import testutils
  from examples.cipher import cipher
label_desc: Use image node_id 1 for calling the CipherTest obj's underlying member method code with example usage: obj.testCipher() without return types