code: def workflow_stages(self) -> List[WorkflowStage]:
          
          workflow_stages = []
          stages = DB.get_hash_value(self.key, 'workflow_stages')
          for index in range(len(ast.literal_eval(stages))):
              workflow_stages.append(WorkflowStage(self.id, index))
          return workflow_stages
docs: Return list of workflow stages.
  
          Returns:
              dict, resources of a specified pb