input: Write a function to visually summarize the Twitter data provided as a stream of tweets with data fields such as tweet author, date of tweet, text, number of likes, and number of retweets. The function should plot summaries for tweet authors, number of likes, and number of retweets using matplotlib.
  
  
  import matplotlib.pyplot as plt
  
  def summarize_twitter_data(twitter_data):
      # Process the Twitter data to extract the relevant data fields
      authors = [tweet['author'] for tweet in twitter_data]
      num_likes = [tweet['num_likes'] for tweet in twitter_data]
      num_retweets = [tweet['num_retweets'] for tweet in twitter_data]
      tweets = range(len(twitter_data))
      
      # Plot the tweet authors
      plt.figure(1)
      plt.xlabel('Tweet Authors')
      plt.ylabel('Number of tweets')
      plt.title('Tweet Author Summary')
      plt.hist(authors)
      plt.show()
      
      # Plot the number of likes
      plt.figure(2)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Likes')
      plt.title('Number of Likes Summary')
      plt.bar(tweets, num_likes)
      plt.show()
      
      # Plot the number of retweets
      plt.figure(3)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Retweets')
      plt.title('Number of Retweets Summary')
      plt.bar(tweets, num_retweets)
      plt.show()
      
  # Example usage
  assert summarize_twitter_data([
      {'author': 'User1', 'date': '2023-01-01', 'text': 'Hello', 'num_likes': 10, 'num_retweets': 2},
      {'author': 'User2', 'date': '2023-01-02', 'text': 'World', 'num_likes': 5, 'num_retweets': 1},
      {'author': 'User1', 'date': '2023-01-03', 'text': 'Python', 'num_likes': 7, 'num_retweets': 3}
  ]) == None
  
  assert summarize_twitter_data([]) == None
  
output: def summarize_twitter_data(twitter_data):
      if not twitter_data:
          return
      
      authors = [tweet['author'] for tweet in twitter_data]
      num_likes = [tweet['num_likes'] for tweet in twitter_data]
      num_retweets = [tweet['num_retweets'] for tweet in twitter_data]
      tweets = range(len(twitter_data))
      
      plt.figure(1)
      plt.xlabel('Tweet Authors')
      plt.ylabel('Number of tweets')
      plt.title('Tweet Author Summary')
      plt.hist(authors)
      plt.show()
      
      plt.figure(2)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Likes')
      plt.title('Number of Likes Summary')
      plt.bar(tweets, num_likes)
      plt.show()
      
      plt.figure(3)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Retweets')
      plt.title('Number of Retweets Summary')
      plt.bar(tweets, num_retweets)
      plt.show()