docs: def empty_group(group_id, scenario_id, **kwargs):
      """
          Delete all itemas in a group, in a scenario.
      """
      user_id = int(kwargs.get('user_id'))
      #check the scenario exists
      _get_scenario(scenario_id, user_id)
  
      rgi = db.DBSession.query(ResourceGroupItem).\
              filter(ResourceGroupItem.group_id==group_id).\
              filter(ResourceGroupItem.scenario_id==scenario_id).all()
      rgi.delete()