class Device(object):        
    def __del__(self):
        print("Device!")


class Vector(object):        
    def __init__(self, device):
        self.device = device
        
    def __del__(self):
        print("Vector!")


class Main(object):
    def __init__(self, device):
        self.vector = Vector(device)


if __name__ == "__main__":
    device = Device()
    a = Main(device)