code: def batch_step_fn(controller: Union["Trainer", "Evaluator"], batch):
      r"""
      对于具体的一个 ``batch`` 的数据，实现训练或者评测过程中的一步；
      """
  
label_desc: Use image node_id 2 for calling the Loop obj's underlying member method code with example usage: obj.batch_step_fn(controller, batch) without return types