code: def get_order_helper(self) -> OrderHelper:
      if not hasattr(self, "_order_helper"):
          # cache to avoid recreate the same instance
          self._order_helper = OrderHelper(self)
      return self._order_helper
  
imports: from __future__ import annotations
  from collections import defaultdict
  from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Type, Union, cast
  from ..utils.index_data import IndexData
  import random
  import numpy
  import pandas
  from qlib.backtest.position import BasePosition
  from ..config import C
  from ..constant import REG_CN, REG_TW
  from ..data.data import D
  from ..log import get_module_logger
  from .decision import Order, OrderDir, OrderHelper
  from .high_performance_ds import BaseQuote, NumpyQuote
label_desc: Use image node_id 26 for calling the Exchange obj's underlying member method code with example usage: obj.get_order_helper() and returns: self