input: Write a function to visually summarize the Twitter data. The function should take as input a stream of tweets with data fields like tweet author, date of tweet, text, number of likes, and number of retweets. It should then process this data to generate plots summarizing the tweet authors, number of likes, and number of retweets. The function should return None but should display the plots.
  assert visually_summarize_twitter_data([{ 'author': 'Alice', 'date': '2023-01-01', 'text': 'Hello World!', 'likes': 10, 'retweets': 2 }, { 'author': 'Bob', 'date': '2023-01-02', 'text': 'Hi There!', 'likes': 5, 'retweets': 1 }])==None
  assert visually_summarize_twitter_data([])==None
output: def visually_summarize_twitter_data(tweets):
      if not tweets:
          return None
      
      authors = [tweet['author'] for tweet in tweets]
      likes = [tweet['likes'] for tweet in tweets]
      retweets = [tweet['retweets'] for tweet in tweets]
      
      import matplotlib.pyplot as plt
      
      plt.figure(figsize=(12, 4))
      
      plt.subplot(1, 3, 1)
      plt.bar(authors, likes)
      plt.title('Number of Likes by Author')
      plt.xlabel('Author')
      plt.ylabel('Likes')
      
      plt.subplot(1, 3, 2)
      plt.bar(authors, retweets)
      plt.title('Number of Retweets by Author')
      plt.xlabel('Author')
      plt.ylabel('Retweets')
      
      plt.subplot(1, 3, 3)
      plt.scatter(likes, retweets)
      plt.title('Likes vs Retweets')
      plt.xlabel('Likes')
      plt.ylabel('Retweets')
      
      plt.tight_layout()
      plt.show()
      
      return None