input: def generate_response(question: str) -> str:
      """This function generates a response to a user's question based on a predefined set of answers.
      If the question is not found in the predefined set, it will return a random response.
      The conversation continues until the user inputs 'Goodbye'.
      >>> generate_response('What is XYZ?')
      'XYZ is a company that provides XYZ services.'
      >>> generate_response('What does XYZ do?')
      'XYZ helps customers find solutions to their problems.'
      >>> generate_response('How is the weather today?')
      'I am not sure I understand.'
      """
output:     predefined_answers = {
          'What is XYZ?': 'XYZ is a company that provides XYZ services.',
          'What does XYZ do?': 'XYZ helps customers find solutions to their problems.',
          'Goodbye': 'Goodbye!'
      }
      
      if question in predefined_answers:
          return predefined_answers[question]
      else:
          return "I am not sure I understand."