code: def set_unset(self, interface_id, attribute, address=None):
          
          interface = self.get(interface_id) if interface_id is not None else None
          if address is not None:
              target_network = None
              sub_interface = interface.all_interfaces.get(address=address)
              if sub_interface:
                  target_network = sub_interface.network_value
  
              if not target_network:
                  raise InterfaceNotFound('Address specified: %s was not found on interface '
                      '%s' % (address, interface_id))
          
          for interface in self:
              all_subs = interface.sub_interfaces()
              for sub_interface in all_subs:
                  # Skip VLAN only interfaces (no addresses)
                  if not isinstance(sub_interface, (VlanInterface, InlineInterface)):
                      if getattr(sub_interface, attribute) is not None:
                          if sub_interface.nicid == str(interface_id):
                              if address is not None:
                                  if sub_interface.network_value == target_network:
                                      sub_interface[attribute] = True
                                  else:
                                      sub_interface[attribute] = False
                              else:
                                  sub_interface[attribute] = True
                          else: #unset
                              sub_interface[attribute] = False
docs: Set attribute to True and unset the same attribute for all other
          interfaces. This is used for interface options that can only be
          set on one engine interface. 
          
          :raises InterfaceNotFound: raise if specified address does not exist or
              if the interface is not supported for this management role (i.e. you
              cannot set primary mgt to a CVI interface with no nodes).