如何在tkinter中清除FigureCanvasTkAgg画布

import tkinter as tk
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

root = tk.Tk()
fig = Figure()
canvas = FigureCanvasTkAgg(fig, master=root)
canvas.get_tk_widget().pack()

ax = fig.add_subplot(111)
ax.plot([1, 2, 3, 4], [1, 4, 9, 16])
canvas.draw()

def clear_canvas():
    ax.clear()
    canvas.draw()

clear_button = tk.Button(root, text="Clear", command=clear_canvas)
clear_button.pack()

import tkinter as tk
from matplotlib.figure import Figure
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

def clear_canvas():
    ax.clear()
    canvas.draw()

root = tk.Tk()
fig = Figure()
canvas = FigureCanvasTkAgg(fig, master=root)
canvas.get_tk_widget().pack()

ax = fig.add_subplot(111)
ax.plot([1, 2, 3, 4], [1, 4, 9, 16])
canvas.draw()

clear_button = tk.Button(root, text="Clear", command=clear_canvas)
clear_button.pack()

tk.mainloop()