code: def __len__(self):
      if hasattr(self, "fitted_models_"):
          return len(self.fitted_models_)
      return 0
  
imports: import numbers
  from joblib import Parallel, delayed
  import numpy
  from scipy.stats import kendalltau, rankdata, spearmanr
  from sklearn.base import BaseEstimator, clone
  from sklearn.model_selection import check_cv
  from sklearn.utils._param_validation import Interval, StrOptions
  from .base import _fit_and_score
  from .stacking import Stacking
label_desc: Use image node_id 2 for calling the BaseEnsembleSelection obj's underlying member method code with example usage: obj.__len__() and returns: int, len