python实现定时器产生随机数

# -*- coding:utf-8 -*-
import threading
import time
import random

cancel_tmr = False
count=0
n=1

def start():
	#具体任务执行内容

    sum=random.randint(1,20)

    return sum

def heart_beat():
	# 打印当前时间

    #print(time.strftime('%Y-%m-%d %H:%M:%S'))

    if not cancel_tmr:
        a=start()
        global count
        global n
        print("第",n,"随机数：",a)
        count+=a

        print("第",n,"次相加结果:",count)
        n+=1

        # 每隔5秒执行一次
        threading.Timer(5, heart_beat).start()
if __name__ == '__main__':
    heart_beat()
    # 15秒后停止定时器
    time.sleep(15)
    cancel_tmr = True