'Unplug virtual interfaces (VIFs) from networks.
The counter action is :func:`plug_vifs`.
:param nova.objects.instance.Instance instance:
The instance which gets VIFs unplugged.
:param nova.network.model.NetworkInfo network_info:
The object which contains information about the VIFs to unplug.
:return: None'

def unplug_vifs(self, instance, network_info):

    raise NotImplementedError()
