Automated action to assign different person on lead/opportunity depending sales team defined stage

I want to make automated action that would assign person on lead/opportunity every time stages is changed depending on what person (user) is chosen for given stage. I know firstly I would need to expand crm.case.stage module, so there you could add users that belong to particular stage. So with that information, automated action would check what user must be assigned if stage changes. Fro example let say there are three stages - first, second and third. So user1 belongs to first stage, user2, belongs to stage2 and three. When stage changes to second, it assigns that lead/opportunity to user2. I think it should looks something like this example (assigns sales team to sales deparament on lead/opportunity): sales_team = self.pool.get('ir.model.data').get_object(cr, uid, 'crm', 'section_sales_department') object.write({'section_id': sales_team.id}) But this action only assigns specific sales team. It would be best to have an approach that universally selects which user needs to be assigned depending on a stage and user added to that stage. Any suggestions?