input: Below is an instruction that describes a task. Write a response that appropriately completes the request.
  
  ### Instruction:
  Write a Python program to visually summarize the Twitter data.
  
  ### Input:
  Twitter data is a stream of tweets with data fields like : tweet author, date of tweet, text, number of likes, number of retweets.
  
  ### Output:
  import matplotlib.pyplot as plt
  
  # Process the Twitter data to extract
  # the relevant data fields
  # ...
  
  # Plot the tweet authors
  plt.xlabel('Tweet Authors')
  plt.ylabel('Number of tweets')
  plt.title('Tweet Author Summary')
  plt.bar(authors, num_tweets)
  plt.show()
  
  # Plot the number of likes
  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.xlabel('Tweets')
  plt.ylabel('Number of Retweets')
  plt.title('Number of Retweets Summary')
  plt.bar(tweets, num_retweets)
  plt.show()
  
  
  import matplotlib.pyplot as plt
  
  def summarize_twitter_data(twitter_data):
      """Summarize the Twitter data by plotting the tweet authors, number of likes, and number of retweets.
      
      >>> data = [
      ...     {"author": "user1", "likes": 10, "retweets": 5},
      ...     {"author": "user2", "likes": 15, "retweets": 7},
      ...     {"author": "user1", "likes": 20, "retweets": 6},
      ... ]
      >>> summarize_twitter_data(data)
      """
      authors = []
      num_tweets = []
      num_likes = []
      num_retweets = []
      
      for tweet in twitter_data:
          if tweet['author'] not in authors:
              authors.append(tweet['author'])
              num_tweets.append(1)
              num_likes.append(tweet['likes'])
              num_retweets.append(tweet['retweets'])
          else:
              index = authors.index(tweet['author'])
              num_tweets[index] += 1
              num_likes[index] += tweet['likes']
              num_retweets[index] += tweet['retweets']
  
      plt.figure(figsize=(10, 5))
      plt.subplot(1, 3, 1)
      plt.xlabel('Tweet Authors')
      plt.ylabel('Number of tweets')
      plt.title('Tweet Author Summary')
      plt.bar(authors, num_tweets)
      plt.show()
  
      plt.figure(figsize=(10, 5))
      plt.subplot(1, 3, 2)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Likes')
      plt.title('Number of Likes Summary')
      plt.bar(authors, num_likes)
      plt.show()
  
      plt.figure(figsize=(10, 5))
      plt.subplot(1, 3, 3)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Retweets')
      plt.title('Number of Retweets Summary')
      plt.bar(authors, num_retweets)
      plt.show()
  
output:     
      plt.figure(figsize=(10, 5))
      plt.subplot(1, 3, 1)
      plt.xlabel('Tweet Authors')
      plt.ylabel('Number of tweets')
      plt.title('Tweet Author Summary')
      plt.bar(authors, num_tweets)
      plt.show()
  
      plt.figure(figsize=(10, 5))
      plt.subplot(1, 3, 2)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Likes')
      plt.title('Number of Likes Summary')
      plt.bar(authors, num_likes)
      plt.show()
  
      plt.figure(figsize=(10, 5))
      plt.subplot(1, 3, 3)
      plt.xlabel('Tweets')
      plt.ylabel('Number of Retweets')
      plt.title('Number of Retweets Summary')
      plt.bar(authors, num_retweets)
      plt.show()
  