code: def validate_cpu_vs_gpu(gpu_fun, cpu_fun, num_outputs=1):
      gpu_pipe = PythonFunctionPipeline(gpu_fun, "gpu", num_outputs)
      cpu_pipe = PythonFunctionPipeline(cpu_fun, "cpu", num_outputs)
      test_utils.compare_pipelines(
          gpu_pipe, cpu_pipe, BATCH_SIZE, ITERS
      )
  
file_path: DALI/dali/test/python/test_gpu_python_function_operator.py
imports: import cupy
  from nvidia.dali.pipeline import Pipeline
  import nvidia.dali.ops
  import nvidia.dali.types
  import numpy
  import test_utils
  import random
  import os
label_desc: Use image node_id 2 for calling a global function with example usage: validate_cpu_vs_gpu(gpu_fun, cpu_fun, num_outputs) without return types