def gen(x=0):
    x = yield from [1,2,3]
    print("checkpoint 1", x)
    x = yield 4
    print("checkpoint 2", x)
    yield from [5,6,7]

def main():
    for i in gen():
        print(i)

main()

def foo(x=-1):
    print("Entering")
    x = yield 42
    print("Got",x)
    x = yield 1024
    print("got",x)
    return 1234

def main(f=None):
    f = foo()
    print('yield 1 got',f.send(None))
    print('yield 2 got',f.send('hello'))
    try:
        f.send('bye') # End of iterator
    except:
        pass # On Python, this throws stop-iteration with 1234

main()

def accumulate(tally=0,next=None):
    print("Entering accumulate")
    while True:
        print("Yielding None")
        next = yield
        print("Got",next)
        if next is None:
            print("Returning tally",tally)
            return tally
        tally += next

def gather_tallies(tallies,tally=None):
    while True:
        tally = yield from accumulate()
        print("Appending",tally)
        tallies.append(tally)

def main(tallies=None,acc=None):
    tallies = []
    acc = gather_tallies(tallies)
    print(next(acc))
    for i in range(4):
        print(acc.send(i))
    acc.send(None)
    for i in range(5):
        acc.send(i)
    acc.send(None)
    print(tallies)
main()