code: def _load_pre_handler(self, path):
      with open(path, "rb") as file_dataset:
          pre_handler = pickle.load(file_dataset)
      return pre_handler
  
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 3 for calling the RollingDataWorkflow obj's underlying member method code with example usage: obj._load_pre_handler(path) and returns: pre_handler