input: Write a python function to plot a bar chart of average scores for three classes.
  assert plot_average_scores([85, 75, 95], [89, 73, 72], [82, 81, 89]) is None
output: def plot_average_scores(class1, class2, class3):
      import matplotlib.pyplot as plt
      import numpy as np
  
      classes = ['Class 1', 'Class 2', 'Class 3']
      averages = [np.mean(class1), np.mean(class2), np.mean(class3)]
  
      plt.bar(classes, averages, color=['blue', 'green', 'red'])
      plt.xlabel('Classes')
      plt.ylabel('Average Scores')
      plt.title('Average Scores for Three Classes')
      plt.ylim(0, 100)
      plt.show()