docstr: Asserts the dictionary has length 1 and returns the only value.
code: def _sole(self, d: Dict[Any, Any]) -> Any:
      """Asserts the dictionary has length 1 and returns the only value."""
      self.assertLen(d, 1)
      return list(d.values())[0]
  
imports: from typing import Any, Dict
  from kfp.pipeline_spec import pipeline_spec_pb2
  import tensorflow
  from tfx import components
  from tfx import v1
  from tfx.dsl.components.common import importer
  from tfx.dsl.components.common import resolver
  from tfx.dsl.context_managers import dsl_context_registry
  from tfx.dsl.experimental.conditionals import conditional
  from tfx.dsl.input_resolution.strategies import latest_artifact_strategy
  from tfx.dsl.input_resolution.strategies import latest_blessed_model_strategy
  from tfx.extensions.google_cloud_big_query.example_gen import component
  from tfx.orchestration import data_types
  from tfx.orchestration.kubeflow import decorators
  from tfx.orchestration.kubeflow.v2 import parameter_utils
  from tfx.orchestration.kubeflow.v2 import step_builder
  from tfx.orchestration.kubeflow.v2 import test_utils
  from tfx.proto import example_gen_pb2
  from tfx.types import channel
  from tfx.types import channel_utils
  from tfx.types import standard_artifacts
label_desc: Use image node_id 1 for calling the StepBuilderTest obj's underlying member method code with example usage: obj._sole(d) and returns: list