class_docstr: Group the objects based on dict
docstr: Reduce grouped dict.
  
  For example: {(A,B): {C1: object, C2: object}} -> {(A,B): object}
  
  Returns:
      dict: reduced dict
code: def reduce(self, *args, **kwargs) -> dict:
      """
      Reduce grouped dict.
  
      For example: {(A,B): {C1: object, C2: object}} -> {(A,B): object}
  
      Returns:
          dict: reduced dict
      """
      if isinstance(getattr(self, "_ens_func", None), Callable):
          return self._ens_func(*args, **kwargs)
      else:
          raise NotImplementedError(
              f"Please specify valid `_ens_func`."
          )
  
file_path: qlib/qlib/model/ens/group.py
imports: from qlib.model.ens.ensemble import Ensemble, RollingEnsemble
  from typing import Callable
  from joblib import Parallel, delayed
label_desc: Use image node_id 3 for calling the Group obj's underlying member method code with example usage: obj.reduce() and returns: self