code: def square_diff(in1, in2):
      return in1 * in1 - in2 * in2
  
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 5 for calling a global function with example usage: square_diff(in1, in2) and returns: unknown