code: def __getitem__(
      self, i: Union[int, slice]
  ) -> Union[CalVT, List[CalVT]]:
      return self.data[i]
  
imports: from typing import Union, List, Dict, Tuple
  import unittest
  import pandas
  import numpy
  import io
  from .data import GetData
  from ..None import init
  from ..constant import REG_CN, REG_TW
  from qlib.data.filter import NameDFilter
  from qlib.data import D
  from qlib.data.data import Cal, DatasetD
  from qlib.data.storage import CalendarStorage, InstrumentStorage, FeatureStorage, CalVT, InstKT, InstVT
label_desc: Use image node_id 3 for calling the MockCalendarStorage obj's underlying member method code with example usage: obj.__getitem__(i) and returns: self