# (1) [] -> ()
foo = (x for x in range(100))
# (2) 通过yield方式创建
def bar_gen():
    for i in range(100):
        yield i # 调用yield就返回一个生成器对象
bar = bar_gen()
for i in range(100):
    x = next(bar) # 通过next()方法每次获得一个生成数据
    print(x, end=' ')
print()
def bar_gen1():
    x = 1
    yield x+1 # 返回数据并暂停, 下一次next()的时候恢复到这里继续执行
    yield x+2
    yield x+3
bar1 = bar_gen1()
x1 = next(bar1)
x2 = next(bar1)
x3 = next(bar1)
print(x1, x2, x3) # 2 3 4