code: def testGraphTraversal_NoRootArtifact_ReturnsEmptyDict(self):
      result = self._run_graph_traversal(
          [], traverse_upstream=True, artifact_type_names=["Model"]
      )
      self.assertEmpty(result)
  
file_path: tfx/tfx/dsl/input_resolution/ops/graph_traversal_op_test.py
imports: from typing import Sequence
  import tensorflow
  from tfx import types
  from tfx.dsl.input_resolution.ops import ops
  from tfx.dsl.input_resolution.ops import test_utils
label_desc: Use image node_id 4 for calling the GraphTraversalOpTest obj's underlying member method code with example usage: obj.testGraphTraversal_NoRootArtifact_ReturnsEmptyDict() without return types