code: def test_non_utilized_external_source_pruning():
      # if all outputs are unused, ES should simply be pruned not preventing pipeline from operation
      for num_outputs in (None, 1, 2, 3, 4):
          yield _test_non_utilized_external_source_pruning, num_outputs
  
imports: import random
  import nvidia.dali.fn
  import nvidia.dali.ops
  import nvidia.dali.types
  import numpy
  from nvidia.dali import Pipeline, pipeline_def
  from test_utils import check_batch
  from nose_utils import raises, assert_warns, assert_raises
  from nvidia.dali.types import DALIDataType
  from numpy.random import default_rng
label_desc: Use image node_id 30 for calling a global function with example usage: test_non_utilized_external_source_pruning() without return types