code: def spark_session():
      return SparkSession.builder.appName(
          "petastorm-copy"
      ).getOrCreate()
  
file_path: petastorm/petastorm/tests/test_copy_dataset.py
imports: import glob
  import os
  import numpy
  import pytest
  from pyspark.sql import SparkSession
  from pyspark.sql.utils import AnalysisException
  from petastorm.reader import make_reader
  from petastorm.tools.copy_dataset import _main, copy_dataset
label_desc: Use image node_id 1 for calling a global function with example usage: spark_session() and returns: SparkSession