def yhui(n):
    a,b,c=0,[1],[1]
    while a<n:
        yield b
        b.append(0)
        c=b
        b=[v+w for v,w in zip(c,reversed(c))]
        a=a+1
    return '结束'#杨辉三角的前n行

def yanghui(n):
    g=yhui(n)
    while True:
        try:
            x=next(g)
            print(x)
        except StopIteration as e:
            print('生成器返回值：',e.value)
            break#生成并打印杨辉三角的前n行