code: def _test_pass_through():
      @pipeline_def
      def pipeline():
          rng = fn.external_source(
              lambda info: np.array(
                  [info.iteration, info.iteration + 1], dtype=np.float32
              ),
              batch=False,
          )
          return fn.per_frame(
              fn.random.uniform(
                  range=rng, device="gpu", shape=(1, 1, 1), seed=42
              )
          )
  
      pipe = pipeline(batch_size=1, num_threads=4, device_id=0)
      pipe.build()
      for i in range(5):
          (out,) = pipe.run()
          [sample] = [np.array(s) for s in out.as_cpu()]
          assert i <= sample[0] < i + 1
  
file_path: DALI/dali/test/python/operator_1/test_per_frame.py
imports: import numpy
  from nvidia.dali import pipeline_def
  import nvidia.dali.fn
  from test_utils import check_batch
  from nose_utils import raises
label_desc: Use image node_id 9 for calling a global function with example usage: _test_pass_through() and returns: fn