input: Write a python function to get user input and respond to different categories of messages.
  assert respond('hello') in ['hello', 'hi', 'hey']
  assert respond('messi') in ['Did you hear about the latest match?', 'Which player do you think is the best?', 'What team do you support?']
  assert respond('unknown') in ['I am sorry, I do not understand what you said.', 'Can you please elaborate?', 'What do you mean?']
output: def respond(message):
      greetings = ['hello', 'hi', 'hey']
      sports_keywords = ['messi', 'ronaldo', 'football', 'soccer']
      default_responses = [
          'I am sorry, I do not understand what you said.',
          'Can you please elaborate?',
          'What do you mean?'
      ]
  
      if message.lower() in greetings:
          return message.lower()
      elif any(keyword in message.lower() for keyword in sports_keywords):
          return 'Did you hear about the latest match?'
      else:
          return default_responses[0]