code: def add_inline_interface(self, interface_id, second_interface_id,
          logical_interface_ref=None, vlan_id=None, second_vlan_id=None, zone_ref=None,
          second_zone_ref=None, failure_mode='normal', comment=None, **kw):
          
          interface_spec = {'interface_id': interface_id, 'second_interface_id': second_interface_id,
              'interface': kw.get('interface') if self._engine.type in ('single_fw', 'fw_cluster')
              else 'inline_interface'}
          
          _interface = {'logical_interface_ref': logical_interface_ref,
              'failure_mode': failure_mode, 'zone_ref': zone_ref, 'second_zone_ref': second_zone_ref,
              'comment': comment}
          
          vlan = {'vlan_id': vlan_id, 'second_vlan_id': second_vlan_id}
          
          try:
              inline_id = '{}-{}'.format(interface_id, second_interface_id)
              interface = self._engine.interface.get(inline_id)
              _interface.update(vlan)
              interface_spec.update(interfaces=[_interface])
              interface._add_interface(**interface_spec)
              return interface.update()
              
          except InterfaceNotFound:
              _interface.update(interfaces=[vlan])
              interface_spec.update(_interface)
              interface = Layer2PhysicalInterface(**interface_spec)
              return self._engine.add_interface(interface)
docs: Add an inline interface pair. This method is only for IPS or L2FW engine
          types.
          
          :param str interface_id: interface id of first interface
          :param str second_interface_id: second interface pair id
          :param str, href logical_interface_ref: logical interface by href or name
          :param str vlan_id: vlan ID for first interface in pair
          :param str second_vlan_id: vlan ID for second interface in pair
          :param str, href zone_ref: zone reference by name or href for first interface
          :param str, href second_zone_ref: zone reference by nae or href for second interface
          :param str failure_mode: normal or bypass
          :param str comment: optional comment
          :raises EngineCommandFailed: failure creating interface
          :return: None