def inside(name):
    for x in range(5): 
        print(name,':',x)
        yield 



def broken():
    print('Begin broken')
    yield inside('broken') 
    print('End broken')


def ok():
    print('Begin ok')
    yield from inside('ok') 
    print('End ok')


class Eventloop:
    coroutines = []
    def run(self):
        while True:
            if len(self.coroutines) == 0:
                break
            for coro in self.coroutines:
                try:
                    next(coro)
                except StopIteration as e:
                    print(coro, 'is end.')
                    self.coroutines.remove(coro)

    def add_coroutine(self, coro):
        self.coroutines.append(coro())


loop = Eventloop()
loop.add_coroutine(broken)
loop.add_coroutine(ok)
if __name__ == '__main__':
    loop.run()

    
Begin broken
Begin ok
ok : 0
End broken
<generator object broken at 0x7f30bf3068e0> is end.
ok : 1
ok : 2
ok : 3
ok : 4
End ok
<generator object ok at 0x7f30bf306990> is end.