code: def test_json_serializable(tmp_directory, nb_plot):
      d = NotebookIntrospector("nb_plot.ipynb").to_json_serializable()
  
      # must return the plain text representation of the plot (i.e. a str with
      # "<Figure size YxZ with 1 Axes>")
      assert "Figure size" in d["a"]
      assert d["b"] == 42
  
file_path: sklearn-evaluation/tests/nb/test_NotebookIntrospector.py
imports: from sklearn_evaluation import NotebookIntrospector
  from IPython.display import HTML, Image
label_desc: Use image node_id 6 for calling a global function with example usage: test_json_serializable(tmp_directory, nb_plot) without return types