code: def testMergeOutputArtifacts_PreservesExternalArtifact(self):
      original_artifact = standard_artifacts.Examples()
      original_artifact.uri = "/a/b/c"
      original_artifact.is_external = True
      updated_artifact_proto = metadata_store_pb2.Artifact(uri="/a/b/c")
      merged_artifact = merge_utils._merge_output_artifact(
          original_artifact, updated_artifact_proto
      )
      self.assertTrue(merged_artifact.is_external)
  
imports: from typing import Dict, Mapping, Optional, Sequence
  from absl.testing import parameterized
  import tensorflow
  from tfx import types
  from tfx.orchestration.portable import merge_utils
  from tfx.orchestration.portable import outputs_utils
  from tfx.types import standard_artifacts
  from tfx.utils import test_case_utils
  from tfx.utils import typing_utils
  from ml_metadata.proto import metadata_store_pb2
label_desc: Use image node_id 3 for calling the MergeUtilsTest obj's underlying member method code with example usage: obj.testMergeOutputArtifacts_PreservesExternalArtifact() without return types