code: def test_subset_raises_opartitions_and_one_split():
      """[Base] SubsetIndex: check raises error on single split of partitions."""
      with np.testing.assert_raises(ValueError):
          SubsetIndex(2, 1, X=X)
  
imports: import os
  import subprocess
  import numpy
  from mlens import config
  from mlens.utils import IdTrain
  from mlens.index import FoldIndex, BlendIndex, SubsetIndex, TemporalIndex, ClusteredSubsetIndex, FullIndex
  from mlens.index.base import partition, prune_train
label_desc: Use image node_id 42 for calling a global function with example usage: test_subset_raises_opartitions_and_one_split() without return types