code: def iter_estimators():
      for submodule in importlib.import_module("river.api").__all__:
  
          def is_estimator(obj):
              return inspect.isclass(obj) and issubclass(
                  obj, base.Estimator
              )
  
          for _, obj in inspect.getmembers(
              importlib.import_module(f"river.{submodule}"),
              is_estimator,
          ):
              yield obj
  
file_path: river/river/test_estimators.py
imports: from __future__ import annotations
  import importlib
  import inspect
  import pytest
  from river import anomaly, base, checks, compat, compose, facto, feature_extraction, feature_selection, imblearn, linear_model, model_selection, multiclass, neighbors, neural_net, preprocessing, time_series
  from sklearn import linear_model
  from river.compat.river_to_sklearn import River2SKLBase
  from river.compat.sklearn_to_river import SKL2RiverBase
label_desc: Use image node_id 1 for calling a global function with example usage: iter_estimators() and returns: unknown