code: def _dump_pre_handler(self, path):
      handler_config = {
          "class": "Alpha158",
          "module_path": "qlib.contrib.data.handler",
          "kwargs": {
              "start_time": self.start_time,
              "end_time": self.end_time,
              "instruments": self.MARKET,
              "infer_processors": [],
              "learn_processors": [],
          },
      }
      pre_handler = init_instance_by_config(handler_config)
      pre_handler.config(dump_all=True)
      pre_handler.to_pickle(path)
  
file_path: qlib/examples/rolling_process_data/workflow.py
imports: import qlib
  import fire
  import pickle
  from datetime import datetime
  from qlib.constant import REG_CN
  from qlib.data.dataset.handler import DataHandlerLP
  from qlib.utils import init_instance_by_config
  from qlib.tests.data import GetData
label_desc: Use image node_id 2 for calling the RollingDataWorkflow obj's underlying member method code with example usage: obj._dump_pre_handler(path) without return types