import gc

def func():
    class TestException(MemoryError):
        pass

    try:
        raise MemoryError
    except MemoryError as exc:
        inst = exc

    # inst = first preallocated MemoryError

    try:
        raise TestException
    except Exception:
        pass

    inst = None

    try:
        raise MemoryError
    except MemoryError as exc:
       pass

    gc.collect()

if __name__ == "__main__":
    func()
    print("ok")