docstr: get all data
  
  Notes
  ------
  if data(storage) does not exist, return empty pd.Series: `return pd.Series(dtype=np.float32)`
docstr_tok: ["get","all","data","Notes","--","--","--","if","data","(","storage",")","does","not","exist",",","return","empty","pd.Series",":","`","return","pd.Series","(","dtype=np.float32",")","`"]
code: def data(self) -> pd.Series:
      """get all data
  
      Notes
      ------
      if data(storage) does not exist, return empty pd.Series: `return pd.Series(dtype=np.float32)`
      """
      raise NotImplementedError(
          "Subclass of FeatureStorage must implement `data` 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 2 for calling the FeatureStorage obj's underlying member method code with example usage: obj.data() without return types