<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def workflow_stages(self) -> List[WorkflowStage]: """Return list of workflow stages. Returns: dict, resources of a specified pb """

        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