def average():

    sum = 0

    count = 0

    avg = 0

    while True:                  #循环

        num = yield avg          #遇到yield就停止，防止一开始除数为0导致崩溃

        sum += num

        count +=1

        avg = sum/count

avg_g = average()               #生成器获取

avg_g.__next__()                #执行生成器的__next__()函数，跳到第一个yield之后

avg1 = avg_g.send(10)           #执行生成器的send()函数，把10带入num,开始执行并返回avg

avg2 = avg_g.send(20)

print(avg1,avg2)

10.0 15.0