docs: def delete_resourcegroupitems(scenario_id, item_ids, **kwargs):
      """
          Delete specified items in a group, in a scenario.
      """
      user_id = int(kwargs.get('user_id'))
      #check the scenario exists
      _get_scenario(scenario_id, user_id)
      for item_id in item_ids:
          rgi = db.DBSession.query(ResourceGroupItem).\
                  filter(ResourceGroupItem.id==item_id).one()
          db.DBSession.delete(rgi)
  
      db.DBSession.flush()