import gevent


def foo():
    print('Running in foo')
    gevent.sleep(0)
    print('Explicit context switch to foo again')


def bar():
    print('Explicit context to bar')
    gevent.sleep(0)  # break here
    print('Implicit context switch back to bar')


if __name__ == '__main__':
    gevent.joinall([
        gevent.spawn(foo),
        gevent.spawn(bar),
    ])
    print('TEST SUCEEDED')