def contextmanager(foo):
    class cls:
        def __init__(self):
            self.it = iter(foo())

        def __enter__(self):
            next(self.it)

        def __exit__(self, exc_type, exc_val, exc_tb):
            if exc_type:
                self.it.throw(exc_type(exc_val))
                return True

        def __call__(self, *args, **kwargs):
            return foo(*args, **kwargs)
    return cls


if __name__ == '__main__':
    pass


@contextmanager
def foo():
    print("__enter__")
    try:
        yield 42
    except Exception as e:
        print(type(e))
        print(str(e))
    finally:
        print("__exit__")
    return


with foo() as i:
    print(i)
    raise ValueError("OOOPS")