coroutine_walrus.py

def corange(end):
    i = 0
    while i < end:
        v = yield i
        if isinstance(v, int):
            end = v
        i += 1

for i in (r := corange(10)):
    print(i)
    if i == 2:
        i = r.send(4)
        print(i)

$ python3 coroutine_walrus.py
1
2
3