code: def test_n_classes_from_model(self, titanic_model):
      n_classes, pred_func, from_model = _check_model(
          titanic_model, None, None
      )
      assert n_classes == 2
      assert callable(pred_func)
      assert from_model
  
imports: import pandas
  import numpy
  import pytest
  from pdpbox.utils import FeatureInfo, _to_rgba, _check_col, _check_dataset, _make_list, _check_model, _check_classes, _check_memory_limit, _check_frac_to_plot, _calc_n_jobs, _get_string, _expand_params_for_interact, _calc_preds, _check_cluster_params, _check_plot_engine, _check_pdp_interact_plot_type
label_desc: Use image node_id 3 for calling the TestCheckModel obj's underlying member method code with example usage: obj.test_n_classes_from_model(titanic_model) without return types