docstr: x.__getitem__(y) <==> x[y]
  
  Notes
  -------
  if data(storage) does not exist:
      if isinstance(i, int):
          return (None, None)
      if isinstance(i,  slice):
          # return empty pd.Series
          return pd.Series(dtype=np.float32)
docstr_tok: ["x.__getitem__","(","y",")","<","==",">","x","[","y","]","Notes","--","--","--","-","if","data","(","storage",")","does","not","exist",":","if","isinstance","(","i",",","int",")",":","return","(","None",",","None",")","if","isinstance","(","i",",","slice",")",":","#","return","empty","pd.Series","return","pd.Series","(","dtype=np.float32",")"]
code: def __getitem__(self, i) -> Union[Tuple[int, float], pd.Series]:
      """x.__getitem__(y) <==> x[y]
  
      Notes
      -------
      if data(storage) does not exist:
          if isinstance(i, int):
              return (None, None)
          if isinstance(i,  slice):
              # return empty pd.Series
              return pd.Series(dtype=np.float32)
      """
      raise NotImplementedError(
          "Subclass of FeatureStorage must implement `__getitem__(i: int)`/`__getitem__(s: slice)` method"
      )
  
imports: import re
  from typing import Iterable, overload, Tuple, List, Text, Union, Dict
  import numpy
  import pandas
  from qlib.log import get_module_logger
label_desc: Use image node_id 11 for calling the FeatureStorage obj's underlying member method code with example usage: obj.__getitem__(i) without return types