if not hasattr(__builtins__,'StopIteration'):
    class StopIteration(Exception):
        pass
    __builtins__.StopIteration = StopIteration

class Awaiter:
    def __iter__(self):
        yield "    Awaiter(): awaitable returns an iterator"
        return "(all done)"

def foo(i,result=None):
    print('    foo(): hi')
    result = yield from i()
    print('      Awaiting result 1:', result)
    result = yield from Awaiter()
    print('      Awaiting result 2:', result)
    result = yield from i()
    print('      Awaiting result 3:', result)
    print('    foo(): bi')
    return "done"

def bar():
    print("    bar(): hello, there, I'm an async function")
    return 42
    yield 0xdeadbeef

def run(coro, scheduled=None, next=None, result=None):
    # Okay, let's see.
    scheduled = [coro]
    print("Starting run loop.")
    while scheduled:
        print("  Popping from scheduled list.")
        next = scheduled.pop(0) # Yes, that's slow, I know.
        try:
            print("  Calling",type(next))
            result = next.send(None)
            if result == next:
                raise StopIteration(result.__finish__())
            print("  Returned with",result)
            scheduled.append(next)
        except StopIteration as e:
            # Stop iteration value should be return value from foo()
            print('Exception:', type(e), e)
    print('Done with run loop.')

run(foo(bar))