input: Write a function that returns a random response from a predefined list of casual responses when provided with a user input, and also includes a simple loop to keep the conversation going until the user inputs 'Goodbye'. Implement the function and provide appropriate test cases.
  
  
  import random
  
  # List of possible answers
  answers = ["That's a great question!", 
             "I'm not sure, but I'll try to find out!", 
             "That sounds interesting, tell me more!", 
             "I have no idea, sorry!"]
  
  def chatbot_response(user_input): 
      # Get a random response from answers
      response = random.choice(answers)
      return response
  
  # Simple loop to keep the conversation going
  while True:
      user_input = input('You: ')
      if user_input == 'Goodbye':
          print('Chatbot: Goodbye!')
          break
      else:
          print('Chatbot: ', chatbot_response(user_input))
  
  
  assert chatbot_response("How are you?") in ["That's a great question!", 
                                              "I'm not sure, but I'll try to find out!", 
                                              "That sounds interesting, tell me more!", 
                                              "I have no idea, sorry!"]
  assert chatbot_response("Tell me a joke.") in ["That's a great question!", 
                                                "I'm not sure, but I'll try to find out!", 
                                                "That sounds interesting, tell me more!", 
                                                "I have no idea, sorry!"]
  assert chatbot_response("What is your favorite color?") in ["That's a great question!", 
                                                             "I'm not sure, but I'll try to find out!", 
                                                             "That sounds interesting, tell me more!", 
                                                             "I have no idea, sorry!"]
  assert chatbot_response("Goodbye") in ["That's a great question!", 
                                        "I'm not sure, but I'll try to find out!", 
                                        "That sounds interesting, tell me more!", 
                                        "I have no idea, sorry!"]
output: import random
  
  def chatbot_response(user_input): 
      answers = ["That's a great question!", 
                 "I'm not sure, but I'll try to find out!", 
                 "That sounds interesting, tell me more!", 
                 "I have no idea, sorry!"]
      response = random.choice(answers)
      return response