class_docstr: Base class for query-by-committee setup.
  Args:
      learner_list: List of ActiveLearner objects to form committee.
      query_strategy: Function to query labels.
      on_transformed: Whether to transform samples with the pipeline defined by each learner's estimator
          when applying the query strategy.
code: def __iter__(self) -> Iterator[BaseLearner]:
      for learner in self.learner_list:
          yield learner
  
imports: import abc
  import sys
  import warnings
  from typing import Any, Callable, Iterator, List, Tuple, Union
  import numpy
  import scipy.sparse
  from modAL.utils.data import data_hstack, modALinput, retrieve_rows
  from sklearn.base import BaseEstimator
  from sklearn.ensemble._base import _BaseHeterogeneousEnsemble
  from sklearn.pipeline import Pipeline
label_desc: Use image node_id 2 for calling the BaseCommittee obj's underlying member method code with example usage: obj.__iter__() without return types