code: def test_nclasses(tf_shadow_clf):
      assert tf_shadow_clf.nclasses() == 2
  
imports: import pytest
  import numpy
  import tensorflow_decision_forests
  from dtreeviz.models.tensorflow_decision_tree import ShadowTensorflowTree
label_desc: Use image node_id 7 for calling a global function with example usage: test_nclasses(tf_shadow_clf) without return types