'Get vifs by instance.
:param context: nova.context.RequestContext
:param instance: nova.objects.instance.Instance
:returns: nova.objects.virtual_interface.VirtualInterfaceList; the
fields address, uuid and net_uuid should be set for each VIF object
in the returned list.'

def get_vifs_by_instance(self, context, instance):

    raise NotImplementedError()
