code: def add_strategy(self):
      print("========== load ==========")
      self.rolling_online_manager = OnlineManager.load(
          self._ROLLING_MANAGER_PATH
      )
      print("========== add strategy ==========")
      strategies = []
      for task in self.add_tasks:
          name_id = task["model"][
              "class"
          ]  # NOTE: Assumption: The model class can specify only one strategy
          strategies.append(
              RollingStrategy(
                  name_id,
                  task,
                  RollingGen(
                      step=self.rolling_step, rtype=RollingGen.ROLL_SD
                  ),
              )
          )
      self.rolling_online_manager.add_strategy(strategies=strategies)
      print("========== dump ==========")
      self.rolling_online_manager.to_pickle(self._ROLLING_MANAGER_PATH)
  
file_path: qlib/examples/online_srv/rolling_online_management.py
imports: import os
  import fire
  import qlib
  from qlib.model.trainer import DelayTrainerR, DelayTrainerRM, TrainerR, TrainerRM, end_task_train, task_train
  from qlib.workflow import R
  from qlib.workflow.online.strategy import RollingStrategy
  from qlib.workflow.task.gen import RollingGen
  from qlib.workflow.online.manager import OnlineManager
  from qlib.tests.config import CSI100_RECORD_XGBOOST_TASK_CONFIG_ROLLING, CSI100_RECORD_LGB_TASK_CONFIG_ROLLING
  from qlib.workflow.task.manage import TaskManager
label_desc: Use image node_id 6 for calling the RollingOnlineExample obj's underlying member method code with example usage: obj.add_strategy() without return types