class_docstr: Group the rolling dict
code: def __init__(self, ens=RollingEnsemble()):
      super().__init__(ens=ens)
  
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 2 to create a new RollingGroup object from inherited base classes: Group with example: obj = RollingGroup(ens)