Matplotlib.axes.Axes.add_callback() in Python

# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
import time


def update():
    plt.get_current_fig_manager().canvas.figure.patch.set_facecolor(str(np.random.random()))
    plt.draw()
    print("Draw at time :", time.time())
    

def start_animation():
    
    timer = fig.canvas.new_timer(interval = 50)
    timer.add_callback(update)
    timer.start()

fig, ax = plt.subplots()
start_animation()
      
ax.set_title('matplotlib.axes.Axes.add_callback() function\
 Example', fontweight ="bold") 

plt.show()

# Implementation of matplotlib function  
from random import randint, choice 
import time 
import matplotlib.pyplot as plt 
import matplotlib.patches as mpatches 
  
  
back_color = "black"
colors = ['red', 'green', 'blue', 'purple'] 
width, height = 4, 4
  
fig, ax = plt.subplots() 
ax.set(xlim =[0, width], ylim =[0, height]) 
  
fig.canvas.draw() 
  
def update(): 
    x = randint(0, width - 1) 
    y = randint(0, height - 1) 
  
    arti = mpatches.Rectangle( 
        (x, y), 1, 1, 
        facecolor = choice(colors), 
        edgecolor = back_color 
    ) 
    ax.add_artist(arti)
    
    ax.draw_artist(arti) 
    fig.canvas.blit(ax.bbox) 
    print("Draw at time :", time.time()) 
  
timer = fig.canvas.new_timer(interval = 1) 
timer.add_callback(update) 
timer.start() 

      
ax.set_title('matplotlib.axes.Axes.add_callback() \
function Example', fontweight ="bold") 

plt.show()