如何扩展matplotlib colorbar来绘制contourf图？

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-2, 2, 100)
y = np.linspace(-2, 2, 100)
X, Y = np.meshgrid(x, y)
Z = np.sin(X) + np.cos(Y)

fig, ax = plt.subplots()

contour = ax.contourf(X, Y, Z)

cbar = plt.colorbar(contour)

cbar.set_label('Z values')
cbar.set_label('Contourf Plot')

plt.show()