input: Write a python function to plot data using matplotlib and test it with given data.
  assert plot_data(['user1', 'user2'], [10, 20], ['tweet1', 'tweet2'], [100, 200], [50, 75]) is None
output: def plot_data(users, followers, tweets, retweets, likes):
      import matplotlib.pyplot as plt
      
      fig, axs = plt.subplots(2, 2, figsize=(10, 8))
      
      axs[0, 0].bar(users, followers, color='blue')
      axs[0, 0].set_title('Followers per User')
      axs[0, 0].set_xlabel('Users')
      axs[0, 0].set_ylabel('Followers')
  
      axs[0, 1].bar(users, [len(t) for t in tweets], color='green')
      axs[0, 1].set_title('Number of Characters per Tweet')
      axs[0, 1].set_xlabel('Users')
      axs[0, 1].set_ylabel('Characters')
      
      axs[1, 0].bar(users, retweets, color='red')
      axs[1, 0].set_title('Retweets per User')
      axs[1, 0].set_xlabel('Users')
      axs[1, 0].set_ylabel('Retweets')
      
      axs[1, 1].bar(users, likes, color='purple')
      axs[1, 1].set_title('Likes per User')
      axs[1, 1].set_xlabel('Users')
      axs[1, 1].set_ylabel('Likes')
      
      plt.tight_layout()
      plt.show()