code: def del_nic(self, nic, sync=True):
          
          LOGGER.debug("OSInstance.del_nic")
          if not sync:
              self.nic_2_rm.append(nic)
          else:
              if nic.id is None:
                  nic.sync()
              if self.id is not None and nic.id is not None:
                  params = {
                      'id': self.id,
                      'nicID': nic.id
                  }
                  args = {'http_operation': 'GET', 'operation_path': 'update/nics/delete', 'parameters': params}
                  response = OSInstanceService.requester.call(args)
                  if response.rc != 0:
                      LOGGER.warning(
                          'OSInstance.del_nic - Problem while updating OS instance ' + self.name +
                          '. Reason: ' + str(response.response_content) + '-' + str(response.error_message) +
                          " (" + str(response.rc) + ")"
                      )
                  else:
                      self.nic_ids.remove(nic.id)
                      nic.nic_osi_id = None
              else:
                  LOGGER.warning(
                      'OSInstance.del_nic - Problem while updating OS instance ' + self.name + '. Reason: NIC ' +
                      nic.name + ' id is None'
                  )
docs: delete nic from this OS instance
          :param nic: the nic to be deleted from this OS instance
          :param sync: If sync=True(default) synchronize with Ariane server. If sync=False,
          add the nic object on list to be removed on next save().
          :return: