code: def test_roc_sub_not_implemented_error(roc_values):
      fpr, tpr = roc_values
  
      roc = plot.ROC(fpr, tpr)
  
      with pytest.raises(NotImplementedError) as excinfo:
          roc.__sub__()
          assert "Not applicable for ROC" in str(excinfo.value)
  
file_path: sklearn-evaluation/tests/test_roc.py
imports: import pytest
  import numpy
  from sklearn_evaluation import plot, __version__
label_desc: Use image node_id 7 for calling a global function with example usage: test_roc_sub_not_implemented_error(roc_values) without return types