code: def testContainsKey(self):
      event = Event(
          type=metadata_store_pb2.Event.PENDING_OUTPUT,
          path=Path(
              steps=[
                  Step(key="foo"),
                  Step(index=0),
              ]
          ),
      )
      with self.subTest("Matching key."):
          self.assertTrue(event_lib.contains_key(event, "foo"))
  
      with self.subTest("Non-matching key."):
          self.assertFalse(event_lib.contains_key(event, "bar"))
  
imports: import itertools
  from absl.testing import parameterized
  import tensorflow
  from tfx.orchestration.portable.mlmd import event_lib
  from ml_metadata.proto import metadata_store_pb2
label_desc: Use image node_id 13 for calling the EventLibTest obj's underlying member method code with example usage: obj.testContainsKey() without return types