An example of Coroutine in Python.

test_coroutine.py

def read_producer(text, coroutines):
    for word in text.split():
        for coroutine in coroutines:
            coroutine.send(word)
    for coroutine in coroutines:
        coroutine.close()


def match_filter(pattern, next_coroutine):
    print("Looking for {0}".format(pattern))
    try:
        while True:
            line = (yield)
            if pattern in line:
                next_coroutine.send(line)
    except GeneratorExit:
        print("Filter Done.")
        next_coroutine.close()


def print_consumer():
    print('Preparing to print')
    try:
        while True:
            line = (yield)
            print(line)
    except GeneratorExit:
        print("Consumer done.")


def main():
    text = "Commending spending is offending to people pending lending!"
    print("Original text: {0}".format(text))

    printer = print_consumer()
    printer.next()
    m1 = match_filter("mend", printer)
    m2 = match_filter("pe", printer)
    m1.next()
    m2.next()
    read_producer(text, [m1, m2])


if __name__ == "__main__":
    main()