code: def define_graph(self):
      self.data = self.inputs()
      out = self.data.gpu() if self.device == "gpu" else self.data
      out = self.dB(out)
      return out
  
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 2 for calling the ToDecibelsPipeline obj's underlying member method code with example usage: obj.define_graph() and returns: out