老师，在使用绘图函数的时候 会有下面的警告 是什么原因啊， 网上一直找不到答案。
警告：UserWarning: The following kwargs were not used by contour: 'linewidth’
plt.contourf(x0, x1, zz, linewidth=5, cmap=custom_cmap)

函数：
def plot_decision_boundary(model, axis):

x0, x1 = np.meshgrid(
    np.linspace(axis[0], axis[1], int((axis[1]-axis[0])*100)).reshape(-1, 1),
    np.linspace(axis[2], axis[3], int((axis[3]-axis[2])*100)).reshape(-1, 1),
)
X_new = np.c_[x0.ravel(), x1.ravel()]

y_predict = model.predict(X_new)
zz = y_predict.reshape(x0.shape)

from matplotlib.colors import ListedColormap
custom_cmap = ListedColormap(['#EF9A9A','#FFF59D','#90CAF9'])

plt.contourf(x0, x1, zz, linewidth=5, cmap=custom_cmap)