input: Write a function to visually summarize the Twitter data by plotting the tweet authors, number of likes, and number of retweets using Matplotlib. The input is a stream of tweets with data fields like tweet author, date of tweet, text, number of likes, and number of retweets. The function should return the plots.
  assert visualize_twitter_data([{'author': 'User1', 'date': '2023-01-01', 'text': 'Hello', 'likes': 10, 'retweets': 5}, {'author': 'User2', 'date': '2023-01-02', 'text': 'Hi', 'likes': 20, 'retweets': 10}])==None
  assert visualize_twitter_data([])==None
output: import matplotlib.pyplot as plt
  
  def visualize_twitter_data(tweets):
      if not tweets:
          return
      
      authors = [tweet['author'] for tweet in tweets]
      likes = [tweet['likes'] for tweet in tweets]
      retweets = [tweet['retweets'] for tweet in tweets]
      
      fig, ax = plt.subplots(2, 1, figsize=(10, 8))
      
      ax[0].bar(authors, likes, color='blue')
      ax[0].set_title('Number of Likes per Author')
      ax[0].set_ylabel('Likes')
      
      ax[1].bar(authors, retweets, color='green')
      ax[1].set_title('Number of Retweets per Author')
      ax[1].set_ylabel('Retweets')
      ax[1].set_xlabel('Authors')
      
      plt.tight_layout()
      plt.show()