input: Write a python function to create a plot of x values and their cubes using matplotlib.
  assert plot_cubes([1, 2, 3, 4, 5], [1, 8, 27, 64, 125]) == None
  assert plot_cubes([0, 1, 2], [0, 1, 8]) == None
  assert plot_cubes([1, 3, 5], [1, 27, 125]) == None
output: def plot_cubes(x_values, y_values):
      import matplotlib.pyplot as plt
  
      plt.plot(x_values, y_values, label='Cubes')
      plt.xlabel('X values')
      plt.ylabel('Y values (Cubes)')
      plt.title('Plot of X values and their Cubes')
      plt.legend()
      plt.grid(True)
      plt.show()