code: def test_is_fit(shadow_dec_tree):
      assert shadow_dec_tree.is_fit()
  
file_path: dtreeviz/testing/testlib/models/test_decision_trees_sk_pipeline.py
imports: import numpy
  import pytest
  from sklearn.tree import DecisionTreeClassifier
  from sklearn.feature_selection import VarianceThreshold
  from sklearn.pipeline import make_pipeline, Pipeline
  from sklearn.preprocessing import PolynomialFeatures
  from dtreeviz.models.sklearn_decision_trees import ShadowSKDTree
  from dtreeviz.utils import _extract_final_feature_names, extract_params_from_pipeline
label_desc: Use image node_id 5 for calling a global function with example usage: test_is_fit(shadow_dec_tree) without return types