code: def con_pipe(data_iterator, contrast_center, dtype, dev="cpu"):
      contrast = contrast_param()
      if contrast_center is None:
          contrast_center = contrast_center_param()
      inp = fn.external_source(source=data_iterator)
      if dev == "gpu":
          inp = inp.gpu()
      return fn.contrast(
          inp,
          contrast=contrast,
          contrast_center=contrast_center,
          dtype=dtype,
      )
  
imports: import nvidia.dali.fn
  from nvidia.dali import pipeline_def
  import nvidia.dali.types
  import numpy
  from test_utils import compare_pipelines, python_function
  from test_utils import RandomDataIterator
  from sequences_test_utils import ArgCb, video_suite_helper
  import random
label_desc: Use image node_id 10 for calling a global function with example usage: con_pipe(data_iterator, contrast_center, dtype, dev) and returns: fn