code: def test_is_classifier(spark_dtree):
      assert (
          spark_dtree.is_classifier() is True
      ), "Spark decision tree should be classifier"
  
imports: import numpy
  import pyspark
  import pytest
  from pyspark.ml.classification import DecisionTreeClassificationModel
  from pyspark.sql import SparkSession
  from dtreeviz.models.spark_decision_tree import ShadowSparkTree
label_desc: Use image node_id 4 for calling a global function with example usage: test_is_classifier(spark_dtree) without return types