AttributeError：'NoneType'对象没有属性'group'问题

Question

大家好，我的代码有问题，它没有运行：

from napalm import get_network_driver


driver = get_network_driver('ios')
device = driver('192.168.112.130', 'abc', '123')
device.open()


device.load_merge_candidate(filename='IOSConfig.txt')
print(device.compare_config())

if len(device.compare_config()) > 0:
    choice = input('\nWould you like commit these changes? [y/n]: ')
    if choice == 'y':
        print('Committing ...')
        device.commit_config()
    else:
        print('Discarding ...')
        device.discard_config()
else:
    print('No difference')

# close the session with the device.
device.close()
print('Done.')

，错误是： AttributeError：'NoneType'对象没有属性'group'