code: def test_transition_adder(
      self,
      n_step: int,
      additional_discount: float,
      first: dm_env.TimeStep,
      steps: Sequence[dm_env.TimeStep],
      expected_transitions: Sequence[types.Transition],
  ):
      env_spec, extras_spec = test_utils.get_specs(steps[0])
      step_spec = structured.create_step_spec(env_spec, extras_spec)
  
      configs = structured.create_n_step_transition_config(
          step_spec=step_spec, n_step=n_step
      )
  
      adder = structured.StructuredAdder(
          client=self.client,
          max_in_flight_items=0,
          configs=configs,
          step_spec=step_spec,
      )
  
      def n_step_from_trajectory(
          trajectory: Sequence[types.Transition],
      ):
          trajectory = tree.unflatten_as(step_spec, trajectory)
          return structured.n_step_from_trajectory(
              trajectory, additional_discount
          )
  
      super().run_test_adder(
          adder=adder,
          first=first,
          steps=steps,
          expected_items=expected_transitions,
          stack_sequence_fields=False,
          item_transform=n_step_from_trajectory,
          signature=sw.infer_signature(configs, step_spec),
      )
  
file_path: acme/acme/adders/reverb/structured_test.py
imports: from typing import Sequence
  from acme import types
  from acme.adders.reverb import sequence
  from acme.adders.reverb import structured
  from acme.adders.reverb import test_cases
  from acme.adders.reverb import test_utils
  import dm_env
  import numpy
  from reverb import structured_writer
  import tree
  from absl.testing import absltest
  from absl.testing import parameterized
label_desc: Use image node_id 2 for calling the StructuredAdderTest obj's underlying member method code with example usage: obj.test_transition_adder(n_step, additional_discount, first, steps, expected_transitions) and returns: structured