code: def test_get_layers():
      """[Utils] testing: test dummy estimator and preprocessing formatting."""
      for p in [False, True]:
          for cls in ["stack", "blend", "subsemble"]:
              layer = EstimatorContainer().get_layer(cls, p, True)
              lc = EstimatorContainer().get_sequential(cls, p, True)
  
              assert isinstance(layer, Layer)
              assert isinstance(lc, Sequential)
  
imports: import numpy
  import os
  from mlens.ensemble.base import Layer, Sequential
  from mlens.utils.dummy import OLS, LogisticRegression, Scale
  from mlens.testing.dummy import ESTIMATORS, PREPROCESSING, ESTIMATORS_PROBA, ECM, ECM_PROBA, InitMixin
  from mlens.testing.dummy import Data, EstimatorContainer
  from mlens.utils import assert_correct_format
  from mlens.utils.formatting import _assert_format, _format_instances
  from mlens.utils.exceptions import NotFittedError
  from mlens.externals.sklearn.base import BaseEstimator
label_desc: Use image node_id 15 for calling a global function with example usage: test_get_layers() without return types