python 如何实现在控制台界面输出动态进度条

import sys
import time
import random
import threading


pro = 0
i = 0
timeout = 20
def progress_1():
    global pro
    k = 1
    while True:
        if k % 2 == 0:
            print("\r%s%s[/][%d]%%" % (">" * pro, " " * (100 - pro), pro), end='')
        else:
            print("\r%s%s[\][%d]%%" % (">" * pro, " " * (100 - pro), pro), end='')
        if pro > 100:
            break
        k += 1
        time.sleep(0.5)
def progress_2():
    global i
    global pro
    global timeout
    while i <= timeout:
        pro = i * 100 // timeout
        time.sleep(random.random() * 5)
        i += 1


t1 = threading.Thread(target=progress_1)
t2 = threading.Thread(target=progress_2)
t2.start()
t1.start()