code: def handle_stage_changed(self, model):
          '''
          handle a stage change in the data model
  
          :param model: the data model that was changed
          '''
          stages = model.get_stages()
          if self.dataman:
              self.dataman.set('stages', stagesf handle_stage_changed(self, model):
          '''
          handle a stage change in the data model
  
          :param model: the data model that was changed
          '''
          stages = model.get_stages()
          if self.dataman:
              self.dataman.set('stages', stages)
docs: handle a stage change in the data model
  
          :param model: the data model that was changed