def customer():

    r=""

    while True:

        n=yield r#，接收生产者的消息，并向消费者发送r

        print("customer receive",n)

        r="ok"

def produce(c):

    c.send(None)#第一次启动协程必须发送None值，否则报如下错误

    #TypeError: can't send non-None value to a just-started generator

    for i in range():

        print("start send to customer",i)

        r=c.send(i)#向消费者发送值

        print("receive customer",r)

c=customer()

produce(c)

start send to customer

customer receive

receive customer ok

start send to customer

customer receive

receive customer ok

start send to customer

customer receive

receive customer ok

start send to customer

customer receive

receive customer ok

start send to customer

customer receive

receive customer ok

start send to customer

customer receive

receive customer ok