code: def __init__(self, device, iterator, batch_size, reference=1.0):
      super().__init__(device, iterator, batch_size)
      self.log = ops.ToDecibels(
          device=device, multiplier=np.log(10), reference=reference
      )
  
imports: from nvidia.dali.pipeline import Pipeline
  import nvidia.dali.ops
  import numpy
  from functools import partial
  from test_utils import compare_pipelines
  from test_utils import RandomDataIterator
  from nose_utils import raises
label_desc: Use image node_id 1 to create a new NLDaliPipeline object from inherited base classes: NaturalLogarithmPipeline with example: obj = NLDaliPipeline(device, iterator, batch_size, reference)