input: Write a python function to interact with a simple chatbot.
  assert interact_with_chatbot(["hi", "how are you?", "bye"]) == ["Hello!", "I'm fine, thank you!", "Goodbye!"]
  assert interact_with_chatbot(["hello", "what's up?", "goodnight"]) == ["Hello!", "Not much, you?", "Goodnight!"]
  assert interact_with_chatbot(["unknown input"]) == ["I don't understand that."]
output: def interact_with_chatbot(messages):
      responses = {
          "hi": "Hello!",
          "hello": "Hello!",
          "how are you?": "I'm fine, thank you!",
          "what's up?": "Not much, you?",
          "bye": "Goodbye!",
          "goodnight": "Goodnight!"
      }
      return [responses.get(message, "I don't understand that.") for message in messages]