'hot unplug virtual interface from running instance.
:param nova.network.model.VIF vif:
The object which has the information about the interface to detach.
:param nova.objects.instance.Instance instance:
The instance which will remove additional network interface.
:param string vm_ref:
The instance\'s reference from hypervisor\'s point of view.
:param string vif_ref:
The interface\'s reference from hypervisor\'s point of view.
:return: None'

def hot_unplug(self, vif, instance, vm_ref, vif_ref):

    pass
