code: def is_fit(self) -> bool:
      if isinstance(
          self.tree_model,
          (
              DecisionTreeClassificationModel,
              DecisionTreeRegressionModel,
          ),
      ):
          return True
      return False
  
imports: from abc import ABC
  from collections import defaultdict
  from typing import List, Mapping
  import numpy
  import pyspark
  from dtreeviz.models.shadow_decision_tree import ShadowDecTree
  from dtreeviz.utils import criterion_remapping
  from pyspark.ml.classification import DecisionTreeClassificationModel
  from pyspark.ml.regression import DecisionTreeRegressionModel
label_desc: Use image node_id 3 for calling the ShadowSparkTree obj's underlying member method code with example usage: obj.is_fit() and returns: False, True