code: def test_check_ensemble_build_lc_none():
      """[Utils] check_ensemble_build : raises error on LC None."""
      lc = clone(LAYER_CONTAINER)
      lc.raise_on_exception = True
      lc.stack = None
  
      np.testing.assert_raises(
          LayerSpecificationError, check_ensemble_build, lc
      )
  
imports: import numpy
  from mlens.externals.sklearn.base import clone
  from mlens.utils.checks import check_ensemble_build, assert_valid_estimator, assert_correct_format, check_initialized
  from mlens.utils.dummy import OLS, Scale
  from mlens.testing import EstimatorContainer
  from mlens.utils.exceptions import LayerSpecificationError, LayerSpecificationWarning, NotFittedError, ParallelProcessingError, ParallelProcessingWarning
label_desc: Use image node_id 3 for calling a global function with example usage: test_check_ensemble_build_lc_none() without return types