复习

def eat():
    print('我吃什么:')
    a=yield '馒头'
    print(a)
    b = yield '大饼'
    print(b)
    c=yield'韭菜盒子'
    print(c)
    print('程序结束')
    yield 'GEME OVER'
gen=eat()               #表达 gen是一个生成器
ret1=gen.__next__()     #这一步进行到a=yield'馒头'
print(ret1)              #print('馒头')
ret2=gen.send('胡辣汤')    #a=yield'馒头' 变成 a='胡辣汤' print('a')
print(ret2)              #ret2= '大饼'  print(ret2)->print('大饼')
ret3=gen.send('狗粮')      #返回到b=yield '大饼'->变成b=yield '狗粮'
print(ret3)
ret4=gen.send('猫粮')   #之后跟上面的原理相同
print(ret4)               #print '韭菜盒子'  ->>>