code: def zscore(x: Union[pd.Series, pd.DataFrame]):
      return (x - x.mean()).div(x.std())
  
file_path: qlib/qlib/utils/data.py
imports: from copy import deepcopy
  from typing import List, Union
  import pandas
  import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: zscore(x) and returns: unknown