# yield返回值, 生成器
def gen():
    for x in ["a", "b", "c"]:
        yield x
for i in gen():
    print(i)
# a b c

# yield接收值, 协程
def gen():
    while True:
        x = yield
        print("x = %s"% x)
g = gen()
next(g)  # 执行到yield， 激活协程 send(None) ”预激(prime)“协程
g.send(10)
g.send(20)
g.send(30)
g.close()
"""
x = 10
x = 20
x = 30
"""

# 调用生成器
def gen():
    yield from ["x", "y", "z"]
for i in gen():
    print(i)
# x y z